Bug 1561326 - Support CSS min/max width/height for top level windows with root HTML element. r=emilio

Helps support migrating from XUL DOM to an HTML DOM structure. I attempted
to remove the early return when the root element is not a XUL element, but
it appears setting the transparency on a non XUL root is still broken
(test widget/tests/test_mouse_scroll.xul started failing on windows).

Differential Revision: https://phabricator.services.mozilla.com/D40734

--HG--
extra : moz-landing-system : lando

layout/generic/nsContainerFrame.cpp

@@ -569,22 +569,7 @@ void nsContainerFrame::SyncWindowProperties(nsPresContext* aPresContext,
   if (aView != rootView) return;
 
   Element* rootElement = aPresContext->Document()->GetRootElement();
-  if (!rootElement || !rootElement->IsXULElement()) {
-    // Scrollframes use native widgets which don't work well with
-    // translucent windows, at least in Windows XP. So if the document
-    // has a root scrollrame it's useless to try to make it transparent,
-    // we'll just get something broken.
-    // nsCSSFrameConstructor::ConstructRootFrame constructs root
-    // scrollframes whenever the root element is not a XUL element, so
-    // we test for that here. We can't just call
-    // presShell->GetRootScrollFrame() since that might not have
-    // been constructed yet.
-    // We can change this to allow translucent toplevel HTML documents
-    // (e.g. to do something like Dashboard widgets), once we
-    // have broad support for translucent scrolled documents, but be
-    // careful because apparently some Firefox extensions expect
-    // openDialog("something.html") to produce an opaque window
-    // even if the HTML doesn't have a background-color set.
+  if (!rootElement) {
     return;
   }
 
@@ -600,12 +585,24 @@ void nsContainerFrame::SyncWindowProperties(nsPresContext* aPresContext,
   RefPtr<nsPresContext> kungFuDeathGrip(aPresContext);
   AutoWeakFrame weak(rootFrame);
 
-  nsTransparencyMode mode =
-      nsLayoutUtils::GetFrameTransparency(aFrame, rootFrame);
-  int32_t shadow = rootFrame->StyleUIReset()->mWindowShadow;
-  nsCOMPtr<nsIWidget> viewWidget = aView->GetWidget();
-  viewWidget->SetTransparencyMode(mode);
-  windowWidget->SetWindowShadowStyle(shadow);
+  if (!aPresContext->PresShell()->GetRootScrollFrame()) {
+    // Scrollframes use native widgets which don't work well with
+    // translucent windows, at least in Windows XP. So if the document
+    // has a root scrollrame it's useless to try to make it transparent,
+    // we'll just get something broken.
+    // We can change this to allow translucent toplevel HTML documents
+    // (e.g. to do something like Dashboard widgets), once we
+    // have broad support for translucent scrolled documents, but be
+    // careful because apparently some Firefox extensions expect
+    // openDialog("something.html") to produce an opaque window
+    // even if the HTML doesn't have a background-color set.
+    nsTransparencyMode mode =
+        nsLayoutUtils::GetFrameTransparency(aFrame, rootFrame);
+    int32_t shadow = rootFrame->StyleUIReset()->mWindowShadow;
+    nsCOMPtr<nsIWidget> viewWidget = aView->GetWidget();
+    viewWidget->SetTransparencyMode(mode);
+    windowWidget->SetWindowShadowStyle(shadow);
+  }
 
   if (!aRC) return;
 
@@ -613,10 +610,27 @@ void nsContainerFrame::SyncWindowProperties(nsPresContext* aPresContext,
     return;
   }
 
-  nsBoxLayoutState aState(aPresContext, aRC);
-  nsSize minSize = rootFrame->GetXULMinSize(aState);
-  nsSize maxSize = rootFrame->GetXULMaxSize(aState);
-
+  nsSize minSize(0, 0);
+  nsSize maxSize(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
+  if (rootElement->IsXULElement()) {
+    nsBoxLayoutState aState(aPresContext, aRC);
+    minSize = rootFrame->GetXULMinSize(aState);
+    maxSize = rootFrame->GetXULMaxSize(aState);
+  } else {
+    auto* pos = rootFrame->StylePosition();
+    if (pos->mMinWidth.ConvertsToLength()) {
+      minSize.width = pos->mMinWidth.ToLength();
+    }
+    if (pos->mMinHeight.ConvertsToLength()) {
+      minSize.height = pos->mMinHeight.ToLength();
+    }
+    if (pos->mMaxWidth.ConvertsToLength()) {
+      maxSize.width = pos->mMaxWidth.ToLength();
+    }
+    if (pos->mMaxHeight.ConvertsToLength()) {
+      maxSize.height = pos->mMaxHeight.ToLength();
+    }
+  }
   SetSizeConstraints(aPresContext, windowWidget, minSize, maxSize);
 #endif
 }