Bug 1417354 - Introduce nsIDocument::GetPresContext(). r=smaug

It would be convenient to get nsPresContext from nsIDocument.

MozReview-Commit-ID: Ei6V3UE8XGr

--HG--
extra : rebase_source : 8d2a917eb62cf341e4e1810451fd01c01dbc3bad

accessible/base/nsCoreUtils.cpp

@@ -185,11 +185,7 @@ nsCoreUtils::GetAccessKeyFor(nsIContent* aContent)
       !aContent->AsElement()->HasAttr(kNameSpaceID_None, nsGkAtoms::accesskey))
     return 0;
 
-  nsIPresShell* presShell = aContent->OwnerDoc()->GetShell();
-  if (!presShell)
-    return 0;
-
-  nsPresContext *presContext = presShell->GetPresContext();
+  nsPresContext* presContext = aContent->OwnerDoc()->GetPresContext();
   if (!presContext)
     return 0;
 

dom/animation/DocumentTimeline.cpp

@@ -262,12 +262,7 @@ DocumentTimeline::ToTimeStamp(const TimeDuration& aTimeDuration) const
 nsRefreshDriver*
 DocumentTimeline::GetRefreshDriver() const
 {
-  nsIPresShell* presShell = mDocument->GetShell();
-  if (MOZ_UNLIKELY(!presShell)) {
-    return nullptr;
-  }
-
-  nsPresContext* presContext = presShell->GetPresContext();
+  nsPresContext* presContext = mDocument->GetPresContext();
   if (MOZ_UNLIKELY(!presContext)) {
     return nullptr;
   }

dom/base/Element.cpp

@@ -1951,15 +1951,12 @@ Element::UnbindFromTree(bool aDeep, bool aNullParent)
   // we're not leaving behind a pointer to ourselves as the PresContext's
   // cached provider of the viewport's scrollbar styles.
   if (document) {
-    nsIPresShell* presShell = document->GetShell();
-    if (presShell) {
-      nsPresContext* presContext = presShell->GetPresContext();
-      if (presContext) {
-        MOZ_ASSERT(this !=
-                   presContext->GetViewportScrollbarStylesOverrideElement(),
-                   "Leaving behind a raw pointer to this element (as having "
-                   "propagated scrollbar styles) - that's dangerous...");
-      }
+    nsPresContext* presContext = document->GetPresContext();
+    if (presContext) {
+      MOZ_ASSERT(this !=
+                 presContext->GetViewportScrollbarStylesOverrideElement(),
+                 "Leaving behind a raw pointer to this element (as having "
+                 "propagated scrollbar styles) - that's dangerous...");
     }
   }
 #endif

dom/base/FragmentOrElement.cpp

@@ -236,11 +236,7 @@ nsIContent::GetDesiredIMEState()
   if (!doc) {
     return IMEState(IMEState::DISABLED);
   }
-  nsIPresShell* ps = doc->GetShell();
-  if (!ps) {
-    return IMEState(IMEState::DISABLED);
-  }
-  nsPresContext* pc = ps->GetPresContext();
+  nsPresContext* pc = doc->GetPresContext();
   if (!pc) {
     return IMEState(IMEState::DISABLED);
   }

dom/base/Location.cpp

@@ -848,9 +848,8 @@ Location::Reload(bool aForceget)
 
     nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
 
-    nsIPresShell *shell;
-    nsPresContext *pcx;
-    if (doc && (shell = doc->GetShell()) && (pcx = shell->GetPresContext())) {
+    nsPresContext* pcx;
+    if (doc && (pcx = doc->GetPresContext())) {
       pcx->RebuildAllStyleData(NS_STYLE_HINT_REFLOW, eRestyle_Subtree);
     }
 

dom/base/PostMessageEvent.cpp

@@ -195,11 +195,8 @@ PostMessageEvent::Dispatch(nsGlobalWindowInner* aTargetWindow, Event* aEvent)
   // happen because then untrusted content can call postMessage on a chrome
   // window if it can get a reference to it.
 
-  nsIPresShell *shell = aTargetWindow->GetExtantDoc()->GetShell();
-  RefPtr<nsPresContext> presContext;
-  if (shell) {
-    presContext = shell->GetPresContext();
-  }
+  RefPtr<nsPresContext> presContext =
+    aTargetWindow->GetExtantDoc()->GetPresContext();
 
   aEvent->SetTrusted(mTrustedCaller);
   WidgetEvent* internalEvent = aEvent->WidgetEventPtr();

dom/base/ResponsiveImageSelector.cpp

@@ -378,8 +378,7 @@ ResponsiveImageSelector::SelectImage(bool aReselect)
   }
 
   nsIDocument* doc = Document();
-  nsIPresShell* shell = doc->GetShell();
-  nsPresContext* pctx = shell ? shell->GetPresContext() : nullptr;
+  nsPresContext* pctx = doc->GetPresContext();
   nsCOMPtr<nsIURI> baseURI = mOwnerNode->GetBaseURI();
 
   if (!pctx || !baseURI) {

dom/base/nsContentUtils.cpp

@@ -6722,11 +6722,8 @@ nsContentUtils::DispatchXULCommand(nsIContent* aTarget,
 {
   NS_ENSURE_STATE(aTarget);
   nsIDocument* doc = aTarget->OwnerDoc();
-  nsIPresShell* shell = doc->GetShell();
-  nsPresContext* presContext = nullptr;
-  if (shell) {
-    presContext = shell->GetPresContext();
-  }
+  nsPresContext* presContext = doc->GetPresContext();
+
   RefPtr<XULCommandEvent> xulCommand = new XULCommandEvent(doc, presContext,
                                                            nullptr);
   xulCommand->InitCommandEvent(NS_LITERAL_STRING("command"), true, true,

dom/base/nsDocument.cpp

@@ -932,19 +932,11 @@ TransferZoomLevels(nsIDocument* aFromDoc,
   MOZ_ASSERT(aFromDoc && aToDoc,
              "transferring zoom levels from/to null doc");
 
-  nsIPresShell* fromShell = aFromDoc->GetShell();
-  if (!fromShell)
-    return;
-
-  nsPresContext* fromCtxt = fromShell->GetPresContext();
+  nsPresContext* fromCtxt = aFromDoc->GetPresContext();
   if (!fromCtxt)
     return;
 
-  nsIPresShell* toShell = aToDoc->GetShell();
-  if (!toShell)
-    return;
-
-  nsPresContext* toCtxt = toShell->GetPresContext();
+  nsPresContext* toCtxt = aToDoc->GetPresContext();
   if (!toCtxt)
     return;
 
@@ -3697,10 +3689,8 @@ nsDocument::SetDocumentCharacterSet(NotNull<const Encoding*> aEncoding)
   if (mCharacterSet != aEncoding) {
     mCharacterSet = aEncoding;
 
-    if (nsIPresShell* shell = GetShell()) {
-      if (nsPresContext* context = shell->GetPresContext()) {
-        context->DispatchCharSetChange(aEncoding);
-      }
+    if (nsPresContext* context = GetPresContext()) {
+      context->DispatchCharSetChange(aEncoding);
     }
   }
 }
@@ -5331,14 +5321,11 @@ nsDocument::DispatchContentLoadedEvents()
         if (innerEvent) {
           nsEventStatus status = nsEventStatus_eIgnore;
 
-          nsIPresShell *shell = parent->GetShell();
-          if (shell) {
-            RefPtr<nsPresContext> context = shell->GetPresContext();
+          RefPtr<nsPresContext> context = parent->GetPresContext();
 
-            if (context) {
-              EventDispatcher::Dispatch(parent, context, innerEvent, event,
-                                        &status);
-            }
+          if (context) {
+            EventDispatcher::Dispatch(parent, context, innerEvent, event,
+                                      &status);
           }
         }
       }
@@ -6745,13 +6732,10 @@ nsDocument::GetAnimationController()
 
   // If there's a presContext then check the animation mode and pause if
   // necessary.
-  nsIPresShell *shell = GetShell();
-  if (mAnimationController && shell) {
-    nsPresContext *context = shell->GetPresContext();
-    if (context &&
-        context->ImageAnimationMode() == imgIContainer::kDontAnimMode) {
-      mAnimationController->Pause(nsSMILTimeContainer::PAUSE_USERPREF);
-    }
+  nsPresContext* context = GetPresContext();
+  if (mAnimationController && context &&
+      context->ImageAnimationMode() == imgIContainer::kDontAnimMode) {
+    mAnimationController->Pause(nsSMILTimeContainer::PAUSE_USERPREF);
   }
 
   // If we're hidden (or being hidden), notify the newly-created animation
@@ -7519,14 +7503,7 @@ already_AddRefed<Event>
 nsIDocument::CreateEvent(const nsAString& aEventType, CallerType aCallerType,
                          ErrorResult& rv) const
 {
-  nsIPresShell *shell = GetShell();
-
-  nsPresContext *presContext = nullptr;
-
-  if (shell) {
-    // Retrieve the context
-    presContext = shell->GetPresContext();
-  }
+  nsPresContext* presContext = GetPresContext();
 
   // Create event even without presContext.
   RefPtr<Event> ev =
@@ -8568,9 +8545,8 @@ DispatchCustomEventWithFlush(nsINode* aTarget, const nsAString& aEventType,
   if (aOnlyChromeDispatch) {
     event->WidgetEventPtr()->mFlags.mOnlyChromeDispatch = true;
   }
-  if (nsIPresShell* shell = aTarget->OwnerDoc()->GetShell()) {
-    shell->GetPresContext()->
-      RefreshDriver()->ScheduleEventDispatch(aTarget, event);
+  if (nsPresContext* presContext = aTarget->OwnerDoc()->GetPresContext()) {
+    presContext->RefreshDriver()->ScheduleEventDispatch(aTarget, event);
   }
 }
 
@@ -10862,10 +10838,8 @@ nsIDocument::DispatchFullscreenError(const char* aMessage)
 static void
 UpdateViewportScrollbarOverrideForFullscreen(nsIDocument* aDoc)
 {
-  if (nsIPresShell* presShell = aDoc->GetShell()) {
-    if (nsPresContext* presContext = presShell->GetPresContext()) {
-      presContext->UpdateViewportScrollbarStylesOverride();
-    }
+  if (nsPresContext* presContext = aDoc->GetPresContext()) {
+    presContext->UpdateViewportScrollbarStylesOverride();
   }
 }
 

dom/base/nsGlobalWindowInner.cpp

@@ -4398,12 +4398,7 @@ nsGlobalWindowInner::DispatchEvent(nsIDOMEvent* aEvent, bool* aRetVal)
   }
 
   // Obtain a presentation shell
-  nsIPresShell *shell = mDoc->GetShell();
-  RefPtr<nsPresContext> presContext;
-  if (shell) {
-    // Retrieve the context
-    presContext = shell->GetPresContext();
-  }
+  RefPtr<nsPresContext> presContext = mDoc->GetPresContext();
 
   nsEventStatus status = nsEventStatus_eIgnore;
   nsresult rv = EventDispatcher::DispatchDOMEvent(ToSupports(this), nullptr,

dom/base/nsHistory.cpp

@@ -189,9 +189,8 @@ nsHistory::Go(int32_t aDelta, ErrorResult& aRv)
 
       nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
 
-      nsIPresShell *shell;
       nsPresContext *pcx;
-      if (doc && (shell = doc->GetShell()) && (pcx = shell->GetPresContext())) {
+      if (doc && (pcx = doc->GetPresContext())) {
         pcx->RebuildAllStyleData(NS_STYLE_HINT_REFLOW, eRestyle_Subtree);
       }
 

dom/base/nsIDocument.h

@@ -913,6 +913,12 @@ public:
       ? mPresShell : nullptr;
   }
 
+  nsPresContext* GetPresContext() const
+  {
+    nsIPresShell* shell = GetShell();
+    return shell ? shell->GetPresContext() : nullptr;
+  }
+
   bool HasShellOrBFCacheEntry() const
   {
     return mPresShell || mBFCacheEntry;

dom/base/nsINode.cpp

@@ -1263,11 +1263,7 @@ nsINode::DispatchEvent(nsIDOMEvent *aEvent, bool* aRetVal)
   }
 
   // Obtain a presentation shell
-  nsIPresShell *shell = document->GetShell();
-  RefPtr<nsPresContext> context;
-  if (shell) {
-    context = shell->GetPresContext();
-  }
+  RefPtr<nsPresContext> context = document->GetPresContext();
 
   nsEventStatus status = nsEventStatus_eIgnore;
   nsresult rv =

dom/base/nsStyleLinkElement.cpp

@@ -227,12 +227,7 @@ nsStyleLinkElement::CheckPreloadAttrs(const nsAttrValue& aAs,
   if (!aMedia.IsEmpty()) {
     RefPtr<MediaList> mediaList = MediaList::Create(aDocument->GetStyleBackendType(),
                                                     aMedia);
-    nsIPresShell* shell = aDocument->GetShell();
-    if (!shell) {
-      return false;
-    }
-
-    nsPresContext* presContext = shell->GetPresContext();
+    nsPresContext* presContext = aDocument->GetPresContext();
     if (!presContext) {
       return false;
     }

dom/browser-element/BrowserElementParent.cpp

@@ -81,11 +81,8 @@ DispatchCustomDOMEvent(Element* aFrameElement, const nsAString& aEventName,
                        nsEventStatus *aStatus)
 {
   NS_ENSURE_TRUE(aFrameElement, false);
-  nsIPresShell *shell = aFrameElement->OwnerDoc()->GetShell();
-  RefPtr<nsPresContext> presContext;
-  if (shell) {
-    presContext = shell->GetPresContext();
-  }
+  RefPtr<nsPresContext> presContext =
+    aFrameElement->OwnerDoc()->GetPresContext();
 
   RefPtr<CustomEvent> event =
     NS_NewDOMCustomEvent(aFrameElement, presContext, nullptr);

dom/events/Event.cpp

@@ -344,9 +344,9 @@ Event::Init(mozilla::dom::EventTarget* aGlobal)
     nsCOMPtr<nsIDocument> d = w->GetExtantDoc();
     if (d) {
       trusted = nsContentUtils::IsChromeDoc(d);
-      nsIPresShell* s = d->GetShell();
-      if (s) {
-        InitPresContextData(s->GetPresContext());
+      nsPresContext* presContext = d->GetPresContext();
+      if (presContext) {
+        InitPresContextData(presContext);
       }
     }
   }

dom/html/HTMLAnchorElement.cpp

@@ -175,13 +175,10 @@ HTMLAnchorElement::IsHTMLFocusable(bool aWithMouse,
   // cannot focus links if there is no link handler
   nsIDocument* doc = GetComposedDoc();
   if (doc) {
-    nsIPresShell* presShell = doc->GetShell();
-    if (presShell) {
-      nsPresContext* presContext = presShell->GetPresContext();
-      if (presContext && !presContext->GetLinkHandler()) {
-        *aIsFocusable = false;
-        return false;
-      }
+    nsPresContext* presContext = doc->GetPresContext();
+    if (presContext && !presContext->GetLinkHandler()) {
+      *aIsFocusable = false;
+      return false;
     }
   }
 

dom/html/HTMLCanvasElement.cpp

@@ -1338,12 +1338,7 @@ HTMLCanvasElement::RegisterFrameCaptureListener(FrameCaptureListener* aListener,
       doc = doc->GetParentDocument();
     }
 
-    nsIPresShell* shell = doc->GetShell();
-    if (!shell) {
-      return NS_ERROR_FAILURE;
-    }
-
-    nsPresContext* context = shell->GetPresContext();
+    nsPresContext* context = doc->GetPresContext();
     if (!context) {
       return NS_ERROR_FAILURE;
     }

dom/html/HTMLMenuElement.cpp

@@ -70,12 +70,11 @@ HTMLMenuElement::SendShowEvent()
   event.mFlags.mBubbles = false;
   event.mFlags.mCancelable = false;
 
-  nsCOMPtr<nsIPresShell> shell = document->GetShell();
-  if (!shell) {
+  RefPtr<nsPresContext> presContext = document->GetPresContext();
+  if (!presContext) {
     return;
   }
 
-  RefPtr<nsPresContext> presContext = shell->GetPresContext();
   nsEventStatus status = nsEventStatus_eIgnore;
   EventDispatcher::Dispatch(static_cast<nsIContent*>(this), presContext,
                             &event, nullptr, &status);

dom/html/HTMLSourceElement.cpp

@@ -43,8 +43,7 @@ bool
 HTMLSourceElement::MatchesCurrentMedia()
 {
   if (mMediaList) {
-    nsIPresShell* presShell = OwnerDoc()->GetShell();
-    nsPresContext* pctx = presShell ? presShell->GetPresContext() : nullptr;
+    nsPresContext* pctx = OwnerDoc()->GetPresContext();
     return pctx && mMediaList->Matches(pctx);
   }
 
@@ -60,8 +59,7 @@ HTMLSourceElement::WouldMatchMediaForDocument(const nsAString& aMedia,
     return true;
   }
 
-  nsIPresShell* presShell = aDocument->GetShell();
-  nsPresContext* pctx = presShell ? presShell->GetPresContext() : nullptr;
+  nsPresContext* pctx = aDocument->GetPresContext();
 
   RefPtr<MediaList> mediaList =
     MediaList::Create(aDocument->GetStyleBackendType(), aMedia);

dom/html/ImageDocument.cpp

@@ -730,12 +730,11 @@ ImageDocument::CheckOverflowing(bool changeState)
    * presentation through style resolution is potentially dangerous.
    */
   {
-    nsIPresShell *shell = GetShell();
-    if (!shell) {
+    nsPresContext* context = GetPresContext();
+    if (!context) {
       return NS_OK;
     }
 
-    nsPresContext *context = shell->GetPresContext();
     nsRect visibleArea = context->GetVisibleArea();
 
     mVisibleWidth = nsPresContext::AppUnitsToFloatCSSPixels(visibleArea.width);

dom/html/nsGenericHTMLElement.cpp

@@ -989,11 +989,7 @@ nsGenericHTMLElement::GetPresContext(PresContextFor aFor)
   nsIDocument* doc = (aFor == eForComposedDoc) ?
     GetComposedDoc() : GetUncomposedDoc();
   if (doc) {
-    // Get presentation shell.
-    nsIPresShell *presShell = doc->GetShell();
-    if (presShell) {
-      return presShell->GetPresContext();
-    }
+    return doc->GetPresContext();
   }
 
   return nullptr;
@@ -2460,13 +2456,9 @@ nsGenericHTMLElement::Click(CallerType aCallerType)
   // Strong in case the event kills it
   nsCOMPtr<nsIDocument> doc = GetComposedDoc();
 
-  nsCOMPtr<nsIPresShell> shell;
   RefPtr<nsPresContext> context;
   if (doc) {
-    shell = doc->GetShell();
-    if (shell) {
-      context = shell->GetPresContext();
-    }
+    context = doc->GetPresContext();
   }
 
   SetHandlingClick();

dom/html/nsHTMLDocument.cpp

@@ -861,12 +861,9 @@ nsHTMLDocument::SetCompatibilityMode(nsCompatibility aMode)
 
   mCompatMode = aMode;
   CSSLoader()->SetCompatibilityMode(mCompatMode);
-  nsCOMPtr<nsIPresShell> shell = GetShell();
-  if (shell) {
-    nsPresContext *pc = shell->GetPresContext();
-    if (pc) {
-      pc->CompatibilityModeChanged();
-    }
+  RefPtr<nsPresContext> pc = GetPresContext();
+  if (pc) {
+    pc->CompatibilityModeChanged();
   }
 }
 

dom/ipc/TabChild.cpp

@@ -1330,12 +1330,9 @@ TabChild::RecvSizeModeChanged(const nsSizeMode& aSizeMode)
     return IPC_OK();
   }
   nsCOMPtr<nsIDocument> document(GetDocument());
-  nsCOMPtr<nsIPresShell> presShell = document->GetShell();
-  if (presShell) {
-    nsPresContext* presContext = presShell->GetPresContext();
-    if (presContext) {
-      presContext->SizeModeChanged(aSizeMode);
-    }
+  nsPresContext* presContext = document->GetPresContext();
+  if (presContext) {
+    presContext->SizeModeChanged(aSizeMode);
   }
   return IPC_OK();
 }
@@ -2380,19 +2377,16 @@ TabChild::RecvHandleAccessKey(const WidgetKeyboardEvent& aEvent,
                               nsTArray<uint32_t>&& aCharCodes)
 {
   nsCOMPtr<nsIDocument> document(GetDocument());
-  nsCOMPtr<nsIPresShell> presShell = document->GetShell();
-  if (presShell) {
-    nsPresContext* pc = presShell->GetPresContext();
-    if (pc) {
-      if (!pc->EventStateManager()->
-                 HandleAccessKey(&(const_cast<WidgetKeyboardEvent&>(aEvent)),
-                                 pc, aCharCodes)) {
-        // If no accesskey was found, inform the parent so that accesskeys on
-        // menus can be handled.
-        WidgetKeyboardEvent localEvent(aEvent);
-        localEvent.mWidget = mPuppetWidget;
-        SendAccessKeyNotHandled(localEvent);
-      }
+  RefPtr<nsPresContext> pc = document->GetPresContext();
+  if (pc) {
+    if (!pc->EventStateManager()->
+               HandleAccessKey(&(const_cast<WidgetKeyboardEvent&>(aEvent)),
+                               pc, aCharCodes)) {
+      // If no accesskey was found, inform the parent so that accesskeys on
+      // menus can be handled.
+      WidgetKeyboardEvent localEvent(aEvent);
+      localEvent.mWidget = mPuppetWidget;
+      SendAccessKeyNotHandled(localEvent);
     }
   }
 
@@ -3276,12 +3270,9 @@ TabChild::RecvUIResolutionChanged(const float& aDpi,
     mPuppetWidget->UpdateBackingScaleCache(aDpi, aRounding, aScale);
   }
   nsCOMPtr<nsIDocument> document(GetDocument());
-  nsCOMPtr<nsIPresShell> presShell = document->GetShell();
-  if (presShell) {
-    RefPtr<nsPresContext> presContext = presShell->GetPresContext();
-    if (presContext) {
-      presContext->UIResolutionChangedSync();
-    }
+  RefPtr<nsPresContext> presContext = document->GetPresContext();
+  if (presContext) {
+    presContext->UIResolutionChangedSync();
   }
 
   ScreenIntSize screenSize = GetInnerSize();
@@ -3304,12 +3295,9 @@ TabChild::RecvThemeChanged(nsTArray<LookAndFeelInt>&& aLookAndFeelIntCache)
 {
   LookAndFeel::SetIntCache(aLookAndFeelIntCache);
   nsCOMPtr<nsIDocument> document(GetDocument());
-  nsCOMPtr<nsIPresShell> presShell = document->GetShell();
-  if (presShell) {
-    RefPtr<nsPresContext> presContext = presShell->GetPresContext();
-    if (presContext) {
-      presContext->ThemeChanged();
-    }
+  RefPtr<nsPresContext> presContext = document->GetPresContext();
+  if (presContext) {
+    presContext->ThemeChanged();
   }
   return IPC_OK();
 }

dom/ipc/TabParent.cpp

@@ -1162,8 +1162,7 @@ TabParent::GetLayoutDeviceToCSSScale()
 {
   nsCOMPtr<nsIContent> content = do_QueryInterface(mFrameElement);
   nsIDocument* doc = (content ? content->OwnerDoc() : nullptr);
-  nsIPresShell* shell = (doc ? doc->GetShell() : nullptr);
-  nsPresContext* ctx = (shell ? shell->GetPresContext() : nullptr);
+  nsPresContext* ctx = (doc ? doc->GetPresContext() : nullptr);
   return LayoutDeviceToCSSScale(ctx
     ? (float)ctx->AppUnitsPerDevPixel() / nsPresContext::AppUnitsPerCSSPixel()
     : 0.0f);
@@ -2158,9 +2157,7 @@ TabParent::RecvReplyKeyEvent(const WidgetKeyboardEvent& aEvent)
   // Here we convert the WidgetEvent that we received to an nsIDOMEvent
   // to be able to dispatch it to the <browser> element as the target element.
   nsIDocument* doc = mFrameElement->OwnerDoc();
-  nsIPresShell* presShell = doc->GetShell();
-  NS_ENSURE_TRUE(presShell, IPC_OK());
-  nsPresContext* presContext = presShell->GetPresContext();
+  nsPresContext* presContext = doc->GetPresContext();
   NS_ENSURE_TRUE(presContext, IPC_OK());
 
   AutoHandlingUserInputStatePusher userInpStatePusher(localEvent.IsTrusted(),

dom/mathml/nsMathMLElement.cpp

@@ -122,9 +122,9 @@ nsMathMLElement::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
       // Rebuild style data for the presshell, because style system
       // optimizations may have taken place assuming MathML was disabled.
       // (See nsRuleNode::CheckSpecifiedProperties.)
-      nsCOMPtr<nsIPresShell> shell = doc->GetShell();
-      if (shell) {
-        shell->GetPresContext()->
+      RefPtr<nsPresContext> presContext = doc->GetPresContext();
+      if (presContext) {
+        presContext->
           PostRebuildAllStyleDataEvent(nsChangeHint(0), eRestyle_Subtree);
       }
     }

dom/plugins/base/nsPluginInstanceOwner.cpp

@@ -421,12 +421,7 @@ NS_IMETHODIMP nsPluginInstanceOwner::GetURL(const char *aURL,
     return NS_ERROR_FAILURE;
   }
 
-  nsIPresShell *presShell = doc->GetShell();
-  if (!presShell) {
-    return NS_ERROR_FAILURE;
-  }
-
-  nsPresContext *presContext = presShell->GetPresContext();
+  nsPresContext* presContext = doc->GetPresContext();
   if (!presContext) {
     return NS_ERROR_FAILURE;
   }

dom/smil/nsSMILAnimationController.cpp

@@ -735,12 +735,7 @@ nsSMILAnimationController::PreTraverseInSubtree(Element* aRoot)
     return false;
   }
 
-  nsIPresShell* shell = mDocument->GetShell();
-  if (!shell) {
-    return false;
-  }
-
-  nsPresContext* context = shell->GetPresContext();
+  nsPresContext* context = mDocument->GetPresContext();
   if (!context) {
     return false;
   }
@@ -818,12 +813,7 @@ nsSMILAnimationController::GetRefreshDriver()
     return nullptr;
   }
 
-  nsIPresShell* shell = mDocument->GetShell();
-  if (!shell) {
-    return nullptr;
-  }
-
-  nsPresContext* context = shell->GetPresContext();
+  nsPresContext* context = mDocument->GetPresContext();
   return context ? context->RefreshDriver() : nullptr;
 }
 

dom/smil/nsSMILCSSValueType.cpp

@@ -665,8 +665,7 @@ GetPresContextForElement(Element* aElem)
     // See bug 534975.
     return nullptr;
   }
-  nsIPresShell* shell = doc->GetShell();
-  return shell ? shell->GetPresContext() : nullptr;
+  return doc->GetPresContext();
 }
 
 #ifdef MOZ_OLD_STYLE

dom/smil/nsSMILTimedElement.cpp

@@ -106,10 +106,7 @@ namespace
       nsPresContext* context = nullptr;
       nsIDocument* doc = mTarget->GetUncomposedDoc();
       if (doc) {
-        nsCOMPtr<nsIPresShell> shell = doc->GetShell();
-        if (shell) {
-          context = shell->GetPresContext();
-        }
+        context = doc->GetPresContext();
       }
 
       return EventDispatcher::Dispatch(mTarget, context, &event);

dom/svg/SVGAElement.cpp

@@ -206,13 +206,10 @@ SVGAElement::IsSVGFocusable(bool* aIsFocusable, int32_t* aTabIndex)
   // cannot focus links if there is no link handler
   nsIDocument* doc = GetComposedDoc();
   if (doc) {
-    nsIPresShell* presShell = doc->GetShell();
-    if (presShell) {
-      nsPresContext* presContext = presShell->GetPresContext();
-      if (presContext && !presContext->GetLinkHandler()) {
-        *aIsFocusable = false;
-        return false;
-      }
+    nsPresContext* presContext = doc->GetPresContext();
+    if (presContext && !presContext->GetLinkHandler()) {
+      *aIsFocusable = false;
+      return false;
     }
   }
 

dom/xul/XULDocument.cpp

@@ -820,14 +820,12 @@ XULDocument::ExecuteOnBroadcastHandlerFor(Element* aBroadcaster,
         // |onbroadcast| event handler
         WidgetEvent event(true, eXULBroadcast);
 
-        nsCOMPtr<nsIPresShell> shell = GetShell();
-        if (shell) {
-            RefPtr<nsPresContext> aPresContext = shell->GetPresContext();
-
-            // Handle the DOM event
-            nsEventStatus status = nsEventStatus_eIgnore;
-            EventDispatcher::Dispatch(child, aPresContext, &event, nullptr,
-                                      &status);
+        RefPtr<nsPresContext> presContext = GetPresContext();
+        if (presContext) {
+          // Handle the DOM event
+          nsEventStatus status = nsEventStatus_eIgnore;
+          EventDispatcher::Dispatch(child, presContext, &event, nullptr,
+                                    &status);
         }
     }
 

dom/xul/nsXULElement.cpp

@@ -1621,10 +1621,9 @@ nsXULElement::ClickWithInputSource(uint16_t aInputSource, bool aIsTrustedEvent)
 
     nsCOMPtr<nsIDocument> doc = GetComposedDoc(); // Strong just in case
     if (doc) {
-        nsCOMPtr<nsIPresShell> shell = doc->GetShell();
-        if (shell) {
+        RefPtr<nsPresContext> context = doc->GetPresContext();
+        if (context) {
             // strong ref to PresContext so events don't destroy it
-            RefPtr<nsPresContext> context = shell->GetPresContext();
 
             WidgetMouseEvent eventDown(aIsTrustedEvent, eMouseDown,
                                        nullptr, WidgetMouseEvent::eReal);
@@ -1776,14 +1775,12 @@ nsXULElement::HideWindowChrome(bool aShouldHide)
     if (!doc->IsRootDisplayDocument())
       return NS_OK;
 
-    nsIPresShell *shell = doc->GetShell();
+    nsPresContext* presContext = doc->GetPresContext();
 
-    if (shell) {
+    if (presContext && presContext->IsChrome()) {
         nsIFrame* frame = GetPrimaryFrame();
 
-        nsPresContext *presContext = shell->GetPresContext();
-
-        if (frame && presContext && presContext->IsChrome()) {
+        if (frame) {
             nsView* view = frame->GetClosestView();
 
             if (view) {

dom/xul/nsXULPopupListener.cpp

@@ -223,13 +223,12 @@ nsXULPopupListener::FireFocusOnTargetContent(nsIDOMNode* aTargetNode, bool aIsTo
   nsCOMPtr<nsIDocument> doc = content->OwnerDoc();
 
   // Get nsIDOMElement for targetNode
-  nsIPresShell *shell = doc->GetShell();
-  if (!shell)
-    return NS_ERROR_FAILURE;
-
   // strong reference to keep this from going away between events
   // XXXbz between what events?  We don't use this local at all!
-  RefPtr<nsPresContext> context = shell->GetPresContext();
+  RefPtr<nsPresContext> context = doc->GetPresContext();
+  if (!context) {
+    return NS_ERROR_FAILURE;
+  }
 
   nsIFrame* targetFrame = content->GetPrimaryFrame();
   if (!targetFrame) return NS_ERROR_FAILURE;

layout/base/PresShell.cpp

@@ -8048,13 +8048,11 @@ PresShell::DispatchTouchEventToDOM(WidgetEvent* aEvent,
       }
     }
 
-    nsIPresShell *presShell = doc->GetShell();
-    if (!presShell) {
+    nsPresContext *context = doc->GetPresContext();
+    if (!context) {
       continue;
     }
 
-    nsPresContext *context = presShell->GetPresContext();
-
     tmpStatus = nsEventStatus_eIgnore;
     EventDispatcher::Dispatch(targetPtr, context,
                               &newEvent, nullptr, &tmpStatus, aEventCB);
@@ -10503,9 +10501,9 @@ void PresShell::QueryIsActive()
       MOZ_ASSERT(!container,
                  "external resource doc shouldn't have its own container");
 
-      nsIPresShell* displayPresShell = displayDoc->GetShell();
-      if (displayPresShell) {
-        container = displayPresShell->GetPresContext()->GetContainerWeak();
+      nsPresContext* displayPresContext = displayDoc->GetPresContext();
+      if (displayPresContext) {
+        container = displayPresContext->GetContainerWeak();
       }
     }
   }

layout/base/nsDocumentViewer.cpp

@@ -1204,11 +1204,7 @@ nsDocumentViewer::PermitUnloadInternal(uint32_t *aPermitUnloadFlags,
 
   // Now, fire an BeforeUnload event to the document and see if it's ok
   // to unload...
-  nsIPresShell* shell = mDocument->GetShell();
-  nsPresContext* presContext = nullptr;
-  if (shell) {
-    presContext = shell->GetPresContext();
-  }
+  nsPresContext* presContext = mDocument->GetPresContext();
   RefPtr<BeforeUnloadEvent> event =
     new BeforeUnloadEvent(mDocument, presContext, nullptr);
   event->InitEvent(NS_LITERAL_STRING("beforeunload"), false, true);
@@ -2664,13 +2660,10 @@ nsDocumentViewer::CreateDeviceContext(nsView* aContainerView)
   if (doc) {
     NS_ASSERTION(!aContainerView, "External resource document embedded somewhere?");
     // We want to use our display document's device context if possible
-    nsIPresShell* shell = doc->GetShell();
-    if (shell) {
-      nsPresContext* ctx = shell->GetPresContext();
-      if (ctx) {
-        mDeviceContext = ctx->DeviceContext();
-        return NS_OK;
-      }
+    nsPresContext* ctx = doc->GetPresContext();
+    if (ctx) {
+      mDeviceContext = ctx->DeviceContext();
+      return NS_OK;
     }
   }
 
@@ -2953,13 +2946,10 @@ static bool
 SetExtResourceTextZoom(nsIDocument* aDocument, void* aClosure)
 {
   // Would it be better to enumerate external resource viewers instead?
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
-      ctxt->SetTextZoom(ZoomInfo->mZoom);
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
+    ctxt->SetTextZoom(ZoomInfo->mZoom);
   }
 
   return true;
@@ -2968,12 +2958,9 @@ SetExtResourceTextZoom(nsIDocument* aDocument, void* aClosure)
 static bool
 SetExtResourceMinFontSize(nsIDocument* aDocument, void* aClosure)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      ctxt->SetBaseMinFontSize(NS_PTR_TO_INT32(aClosure));
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    ctxt->SetBaseMinFontSize(NS_PTR_TO_INT32(aClosure));
   }
 
   return true;
@@ -2983,13 +2970,10 @@ static bool
 SetExtResourceFullZoom(nsIDocument* aDocument, void* aClosure)
 {
   // Would it be better to enumerate external resource viewers instead?
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
-      ctxt->SetFullZoom(ZoomInfo->mZoom);
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
+    ctxt->SetFullZoom(ZoomInfo->mZoom);
   }
 
   return true;
@@ -2998,13 +2982,10 @@ SetExtResourceFullZoom(nsIDocument* aDocument, void* aClosure)
 static bool
 SetExtResourceOverrideDPPX(nsIDocument* aDocument, void* aClosure)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
-      ctxt->SetOverrideDPPX(ZoomInfo->mZoom);
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    struct ZoomInfo* ZoomInfo = static_cast<struct ZoomInfo*>(aClosure);
+    ctxt->SetOverrideDPPX(ZoomInfo->mZoom);
   }
 
   return true;
@@ -3273,13 +3254,10 @@ nsDocumentViewer::GetAuthorStyleDisabled(bool* aStyleDisabled)
 static bool
 ExtResourceEmulateMedium(nsIDocument* aDocument, void* aClosure)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      const nsAString* mediaType = static_cast<nsAString*>(aClosure);
-      ctxt->EmulateMedium(*mediaType);
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    const nsAString* mediaType = static_cast<nsAString*>(aClosure);
+    ctxt->EmulateMedium(*mediaType);
   }
 
   return true;
@@ -3311,12 +3289,9 @@ nsDocumentViewer::EmulateMedium(const nsAString& aMediaType)
 static bool
 ExtResourceStopEmulatingMedium(nsIDocument* aDocument, void* aClosure)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* ctxt = shell->GetPresContext();
-    if (ctxt) {
-      ctxt->StopEmulatingMedium();
-    }
+  nsPresContext* ctxt = aDocument->GetPresContext();
+  if (ctxt) {
+    ctxt->StopEmulatingMedium();
   }
 
   return true;

layout/base/nsLayoutUtils.cpp

@@ -8447,9 +8447,9 @@ nsLayoutUtils::PostRestyleEvent(Element* aElement,
 {
   nsIDocument* doc = aElement->GetComposedDoc();
   if (doc) {
-    nsCOMPtr<nsIPresShell> presShell = doc->GetShell();
-    if (presShell) {
-      presShell->GetPresContext()->RestyleManager()->PostRestyleEvent(
+    RefPtr<nsPresContext> presContext = doc->GetPresContext();
+    if (presContext) {
+      presContext->RestyleManager()->PostRestyleEvent(
         aElement, aRestyleHint, aMinChangeHint);
     }
   }

layout/base/nsPresContext.cpp

@@ -907,10 +907,9 @@ nsPresContext::Init(nsDeviceContext* aDeviceContext)
   mAnimationManager = new nsAnimationManager(this);
 
   if (mDocument->GetDisplayDocument()) {
-    NS_ASSERTION(mDocument->GetDisplayDocument()->GetShell() &&
-                 mDocument->GetDisplayDocument()->GetShell()->GetPresContext(),
+    NS_ASSERTION(mDocument->GetDisplayDocument()->GetPresContext(),
                  "Why are we being initialized?");
-    mRefreshDriver = mDocument->GetDisplayDocument()->GetShell()->
+    mRefreshDriver = mDocument->GetDisplayDocument()->
       GetPresContext()->RefreshDriver();
   } else {
     nsIDocument* parent = mDocument->GetParentDocument();
@@ -921,10 +920,7 @@ nsPresContext::Init(nsDeviceContext* aDeviceContext)
     NS_ASSERTION(!parent || mDocument->IsStaticDocument() || parent->GetShell(),
                  "How did we end up with a presshell if our parent doesn't "
                  "have one?");
-    if (parent && parent->GetShell()) {
-      NS_ASSERTION(parent->GetShell()->GetPresContext(),
-                   "How did we get a presshell?");
-
+    if (parent && parent->GetPresContext()) {
       // We don't have our container set yet at this point
       nsCOMPtr<nsIDocShellTreeItem> ourItem = mDocument->GetDocShell();
       if (ourItem) {
@@ -937,7 +933,7 @@ nsPresContext::Init(nsDeviceContext* aDeviceContext)
               !containingElement->
                 HasAttr(kNameSpaceID_None,
                         nsGkAtoms::forceOwnRefreshDriver)) {
-            mRefreshDriver = parent->GetShell()->GetPresContext()->RefreshDriver();
+            mRefreshDriver = parent->GetPresContext()->RefreshDriver();
           }
         }
       }
@@ -1961,17 +1957,14 @@ nsPresContext::UIResolutionChangedSync()
 nsPresContext::UIResolutionChangedSubdocumentCallback(nsIDocument* aDocument,
                                                       void* aData)
 {
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* pc = shell->GetPresContext();
-    if (pc) {
-      // For subdocuments, we want to apply the parent's scale, because there
-      // are cases where the subdoc's device context is connected to a widget
-      // that has an out-of-date resolution (it's on a different screen, but
-      // currently hidden, and will not be updated until shown): bug 1249279.
-      double scale = *static_cast<double*>(aData);
-      pc->UIResolutionChangedInternalScale(scale);
-    }
+  nsPresContext* pc = aDocument->GetPresContext();
+  if (pc) {
+    // For subdocuments, we want to apply the parent's scale, because there
+    // are cases where the subdoc's device context is connected to a widget
+    // that has an out-of-date resolution (it's on a different screen, but
+    // currently hidden, and will not be updated until shown): bug 1249279.
+    double scale = *static_cast<double*>(aData);
+    pc->UIResolutionChangedInternalScale(scale);
   }
   return true;
 }
@@ -2122,10 +2115,8 @@ static bool
 MediaFeatureValuesChangedAllDocumentsCallback(nsIDocument* aDocument, void* aChange)
 {
   auto* change = static_cast<const MediaFeatureChange*>(aChange);
-  if (nsIPresShell* shell = aDocument->GetShell()) {
-    if (nsPresContext* pc = shell->GetPresContext()) {
-      pc->MediaFeatureValuesChangedAllDocuments(*change);
-    }
+  if (nsPresContext* pc = aDocument->GetPresContext()) {
+    pc->MediaFeatureValuesChangedAllDocuments(*change);
   }
   return true;
 }
@@ -2494,16 +2485,13 @@ static bool
 MayHavePaintEventListenerSubdocumentCallback(nsIDocument* aDocument, void* aData)
 {
   bool *result = static_cast<bool*>(aData);
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* pc = shell->GetPresContext();
-    if (pc) {
-      *result = pc->MayHavePaintEventListenerInSubDocument();
+  nsPresContext* pc = aDocument->GetPresContext();
+  if (pc) {
+    *result = pc->MayHavePaintEventListenerInSubDocument();
 
-      // If we found a paint event listener, then we can stop enumerating
-      // sub documents.
-      return !*result;
-    }
+    // If we found a paint event listener, then we can stop enumerating
+    // sub documents.
+    return !*result;
   }
   return true;
 }
@@ -2690,13 +2678,10 @@ nsPresContext::NotifyDidPaintSubdocumentCallback(nsIDocument* aDocument, void* a
 {
   NotifyDidPaintSubdocumentCallbackClosure* closure =
     static_cast<NotifyDidPaintSubdocumentCallbackClosure*>(aData);
-  nsIPresShell* shell = aDocument->GetShell();
-  if (shell) {
-    nsPresContext* pc = shell->GetPresContext();
-    if (pc) {
-      pc->NotifyDidPaintForSubtree(closure->mTransactionId,
-                                   closure->mTimeStamp);
-    }
+  nsPresContext* pc = aDocument->GetPresContext();
+  if (pc) {
+    pc->NotifyDidPaintForSubtree(closure->mTransactionId,
+                                 closure->mTimeStamp);
   }
   return true;
 }

layout/inspector/inLayoutUtils.cpp

@@ -25,11 +25,11 @@ EventStateManager*
 inLayoutUtils::GetEventStateManagerFor(Element& aElement)
 {
   nsIDocument* doc = aElement.OwnerDoc();
-  nsIPresShell* shell = doc->GetShell();
-  if (!shell)
+  nsPresContext* presContext = doc->GetPresContext();
+  if (!presContext)
     return nullptr;
 
-  return shell->GetPresContext()->EventStateManager();
+  return presContext->EventStateManager();
 }
 
 nsIDOMDocument*

layout/style/FontFaceSet.cpp

@@ -1889,8 +1889,7 @@ FontFaceSet::GetPresContext()
     return nullptr;
   }
 
-  nsIPresShell* shell = mDocument->GetShell();
-  return shell ? shell->GetPresContext() : nullptr;
+  return mDocument->GetPresContext();
 }
 
 void

layout/style/ImageLoader.cpp

@@ -306,12 +306,7 @@ ImageLoader::GetPresContext()
     return nullptr;
   }
 
-  nsIPresShell* shell = mDocument->GetShell();
-  if (!shell) {
-    return nullptr;
-  }
-
-  return shell->GetPresContext();
+  return mDocument->GetPresContext();
 }
 
 static bool

layout/style/MediaQueryList.cpp

@@ -155,13 +155,7 @@ MediaQueryList::RecomputeMatches()
     }
   }
 
-  nsIPresShell* shell = mDocument->GetShell();
-  if (!shell) {
-    // XXXbz What's the right behavior here?  Spec doesn't say.
-    return;
-  }
-
-  nsPresContext* presContext = shell->GetPresContext();
+  nsPresContext* presContext = mDocument->GetPresContext();
   if (!presContext) {
     // XXXbz What's the right behavior here?  Spec doesn't say.
     return;

layout/style/ServoBindings.cpp

@@ -571,10 +571,10 @@ Gecko_GetAnimationRule(RawGeckoElementBorrowed aElement,
   MOZ_ASSERT(aElement);
 
   nsIDocument* doc = aElement->GetComposedDoc();
-  if (!doc || !doc->GetShell()) {
+  if (!doc) {
     return false;
   }
-  nsPresContext* presContext = doc->GetShell()->GetPresContext();
+  nsPresContext* presContext = doc->GetPresContext();
   if (!presContext || !presContext->IsDynamic()) {
     // For print or print preview, ignore animations.
     return false;

layout/style/ServoSpecifiedValues.cpp

@@ -34,10 +34,8 @@ ServoSpecifiedValues::SetIdentAtomValue(nsCSSPropertyID aId, nsAtom* aValue)
     // FIXME(emilio): Can we move mapped attribute declarations across
     // documents? Isn't this wrong in that case? This is pretty out of place
     // anyway.
-    if (nsIPresShell* shell = mDocument->GetShell()) {
-      if (nsPresContext* pc = shell->GetPresContext()) {
-        pc->ForceCacheLang(aValue);
-      }
+    if (nsPresContext* pc = mDocument->GetPresContext()) {
+      pc->ForceCacheLang(aValue);
     }
   }
 }

layout/style/ServoStyleSet.cpp

@@ -124,12 +124,7 @@ ServoStyleSet::GetPresContext()
     return nullptr;
   }
 
-  auto* shell = mDocument->GetShell();
-  if (!shell) {
-    return nullptr;
-  }
-
-  return shell->GetPresContext();
+  return mDocument->GetPresContext();
 }
 
 void

layout/style/nsHTMLStyleSheet.cpp

@@ -510,8 +510,7 @@ nsHTMLStyleSheet::ImplLinkColorSetter(
     return NS_OK;
   }
 
-  RestyleManager* restyle =
-    mDocument->GetShell()->GetPresContext()->RestyleManager();
+  RestyleManager* restyle = mDocument->GetPresContext()->RestyleManager();
 
   if (restyle->IsServo()) {
     MOZ_ASSERT(!ServoStyleSet::IsInServoTraversal());

layout/style/nsMediaFeatures.cpp

@@ -87,22 +87,11 @@ const OperatingSystemVersionInfo kOsVersionStrings[] = {
 };
 #endif
 
-static nsPresContext*
-GetPresContext(nsIDocument* aDocument)
-{
-  nsIPresShell* presShell = aDocument->GetShell();
-  if (!presShell) {
-    return nullptr;
-  }
-
-  return presShell->GetPresContext();
-}
-
 // A helper for four features below
 static nsSize
 GetSize(nsIDocument* aDocument)
 {
-  nsPresContext* pc = GetPresContext(aDocument);
+  nsPresContext* pc = aDocument->GetPresContext();
 
   // Per spec, return a 0x0 viewport if we're not being rendered. See:
   //
@@ -158,7 +147,7 @@ GetDeviceSize(nsIDocument* aDocument)
     return GetSize(aDocument);
   }
 
-  nsPresContext* pc = GetPresContext(aDocument);
+  nsPresContext* pc = aDocument->GetPresContext();
   // NOTE(emilio): We should probably figure out how to return an appropriate
   // device size here, though in a multi-screen world that makes no sense
   // really.
@@ -252,7 +241,7 @@ GetDeviceAspectRatio(nsIDocument* aDocument, const nsMediaFeature*,
 static nsDeviceContext*
 GetDeviceContextFor(nsIDocument* aDocument)
 {
-  nsPresContext* pc = GetPresContext(aDocument);
+  nsPresContext* pc = aDocument->GetPresContext();
   if (!pc) {
     return nullptr;
   }

layout/xul/nsImageBoxFrame.cpp

@@ -86,12 +86,7 @@ private:
 NS_IMETHODIMP
 nsImageBoxFrameEvent::Run()
 {
-  nsIPresShell *pres_shell = mContent->OwnerDoc()->GetShell();
-  if (!pres_shell) {
-    return NS_OK;
-  }
-
-  RefPtr<nsPresContext> pres_context = pres_shell->GetPresContext();
+  RefPtr<nsPresContext> pres_context = mContent->OwnerDoc()->GetPresContext();
   if (!pres_context) {
     return NS_OK;
   }

layout/xul/nsXULPopupManager.cpp

@@ -2791,13 +2791,10 @@ nsXULPopupHidingEvent::Run()
 
   nsIDocument *document = mPopup->GetUncomposedDoc();
   if (pm && document) {
-    nsIPresShell* presShell = document->GetShell();
-    if (presShell) {
-      nsPresContext* context = presShell->GetPresContext();
-      if (context) {
-        pm->FirePopupHidingEvent(mPopup, mNextPopup, mLastPopup,
-                                 context, mPopupType, mDeselectMenu, mIsRollup);
-      }
+    nsPresContext* context = document->GetPresContext();
+    if (context) {
+      pm->FirePopupHidingEvent(mPopup, mNextPopup, mLastPopup,
+                               context, mPopupType, mDeselectMenu, mIsRollup);
     }
   }
 

parser/html/nsHtml5SVGLoadDispatcher.cpp

@@ -28,11 +28,7 @@ nsHtml5SVGLoadDispatcher::Run()
   // That is, should this code flush or something?  Does it really matter?
   // For that matter, do we really want to try getting the prescontext?
   // Does this event ever want one?
-  RefPtr<nsPresContext> ctx;
-  nsCOMPtr<nsIPresShell> shell = mElement->OwnerDoc()->GetShell();
-  if (shell) {
-    ctx = shell->GetPresContext();
-  }
+  RefPtr<nsPresContext> ctx = mElement->OwnerDoc()->GetPresContext();
   EventDispatcher::Dispatch(mElement, ctx, &event);
   // Unblocking onload on the same document that it was blocked even if
   // the element has moved between docs since blocking.

toolkit/components/windowwatcher/nsWindowWatcher.cpp

@@ -2266,10 +2266,8 @@ nsWindowWatcher::SizeOpenedWindow(nsIDocShellTreeOwner* aTreeOwner,
   if (aParent && aOpenerFullZoom.isNothing()) {
     nsCOMPtr<nsPIDOMWindowOuter> piWindow = nsPIDOMWindowOuter::From(aParent);
     if (nsIDocument* doc = piWindow->GetDoc()) {
-      if (nsIPresShell* shell = doc->GetShell()) {
-        if (nsPresContext* presContext = shell->GetPresContext()) {
-          openerZoom = presContext->GetFullZoom();
-        }
+      if (nsPresContext* presContext = doc->GetPresContext()) {
+        openerZoom = presContext->GetFullZoom();
       }
     }
   }

uriloader/base/nsDocLoader.cpp

@@ -691,13 +691,10 @@ void nsDocLoader::DocLoaderIsEmpty(bool aFlushLayout)
         // no matter what.  If we have user fonts, we also need to flush layout,
         // since the reflow is what starts font loads.
         mozilla::FlushType flushType = mozilla::FlushType::Style;
-        nsIPresShell* shell = doc->GetShell();
-        if (shell) {
-          // Be safe in case this presshell is in teardown now
-          nsPresContext* presContext = shell->GetPresContext();
-          if (presContext && presContext->GetUserFontSet()) {
-            flushType = mozilla::FlushType::Layout;
-          }
+        // Be safe in case this presshell is in teardown now
+        nsPresContext* presContext = doc->GetPresContext();
+        if (presContext && presContext->GetUserFontSet()) {
+          flushType = mozilla::FlushType::Layout;
         }
         mDontFlushLayout = mIsFlushingLayout = true;
         doc->FlushPendingNotifications(flushType);