Bug 1344386 - Don't look for overlapping change hints in stylo documents. r=emilio

MozReview-Commit-ID: 9wK8TTXolPM

layout/base/GeckoRestyleManager.cpp

@@ -3472,7 +3472,7 @@ GeckoRestyleManager::ComputeAndProcessStyleChange(
     const RestyleHintData& aRestyleHintData)
 {
   MOZ_ASSERT(mReframingStyleContexts, "should have rsc");
-  nsStyleChangeList changeList;
+  nsStyleChangeList changeList(StyleBackendType::Gecko);
   nsTArray<ElementRestyler::ContextToClear> contextsToClear;
 
   // swappedStructOwners needs to be kept alive until after
@@ -3517,7 +3517,7 @@ GeckoRestyleManager::ComputeAndProcessStyleChange(
   // ProcessRestyledFrames and ClearCachedInheritedStyleDataOnDescendants
   // calls; see comment in ElementRestyler::Restyle.
   nsTArray<RefPtr<nsStyleContext>> swappedStructOwners;
-  nsStyleChangeList changeList;
+  nsStyleChangeList changeList(StyleBackendType::Gecko);
   ElementRestyler r(frame->PresContext(), aElement, &changeList, aMinChange,
                     aRestyleTracker, selectorsForDescendants, treeMatchContext,
                     visibleKidsOfHiddenElement, contextsToClear,

layout/base/PresShell.cpp

@@ -2943,7 +2943,7 @@ PresShell::RecreateFramesFor(nsIContent* aContent)
 
   nsAutoScriptBlocker scriptBlocker;
 
-  nsStyleChangeList changeList;
+  nsStyleChangeList changeList(mPresContext->StyleSet()->BackendType());
   changeList.AppendChange(nullptr, aContent, nsChangeHint_ReconstructFrame);
 
   // Mark ourselves as not safe to flush while we're doing frame construction.
@@ -9585,7 +9585,7 @@ PresShell::Observe(nsISupports* aSubject,
 
         // Because "chrome:" URL equality is messy, reframe image box
         // frames (hack!).
-        nsStyleChangeList changeList;
+        nsStyleChangeList changeList(mPresContext->StyleSet()->BackendType());
         WalkFramesThroughPlaceholders(mPresContext, rootFrame,
                                       ReframeImageBoxes, &changeList);
         // Mark ourselves as not safe to flush while we're doing frame

layout/base/RestyleTracker.cpp

@@ -98,7 +98,7 @@ RestyleTracker::ProcessOneRestyle(Element* aElement,
              (primaryFrame ||
               (aChangeHint & nsChangeHint_ReconstructFrame))) {
     // Don't need to recompute style; just apply the hint
-    nsStyleChangeList changeList;
+    nsStyleChangeList changeList(StyleBackendType::Gecko);
     changeList.AppendChange(primaryFrame, aElement, aChangeHint);
     mRestyleManager->ProcessRestyledFrames(changeList);
   }

layout/base/ServoRestyleManager.cpp

@@ -387,7 +387,7 @@ ServoRestyleManager::ProcessPendingRestyles()
 
     // Recreate style contexts, and queue up change hints (which also handle
     // lazy frame construction).
-    nsStyleChangeList currentChanges;
+    nsStyleChangeList currentChanges(StyleBackendType::Servo);
     DocumentStyleRootIterator iter(doc);
     while (Element* root = iter.GetNextStyleRoot()) {
       ProcessPostTraversal(root, nullptr, styleSet, currentChanges);

layout/base/nsStyleChangeList.cpp

@@ -41,9 +41,17 @@ nsStyleChangeList::AppendChange(nsIFrame* aFrame, nsIContent* aContent, nsChange
              (aHint & nsChangeHint_NeedReflow),
              "Reflow hint bits set without actually asking for a reflow");
 
-  // Filter out all other changes for same content
-  if (!IsEmpty() && (aHint & nsChangeHint_ReconstructFrame)) {
-    if (aContent) {
+  // If Servo fires reconstruct at a node, it is the only change hint fired at
+  // that node.
+  if (IsServo()) {
+    for (size_t i = 0; i < Length(); ++i) {
+      MOZ_ASSERT_IF(aContent && ((aHint | (*this)[i].mHint) & nsChangeHint_ReconstructFrame),
+                    (*this)[i].mContent != aContent);
+    }
+  } else {
+    // Filter out all other changes for same content for Gecko (Servo asserts against this
+    // case above).
+    if (aContent && (aHint & nsChangeHint_ReconstructFrame)) {
       // NOTE: This is captured by reference to please static analysis.
       // Capturing it by value as a pointer should be fine in this case.
       RemoveElementsBy([&](const nsStyleChangeData& aData) {

layout/base/nsStyleChangeList.h

@@ -12,6 +12,7 @@
 #define nsStyleChangeList_h___
 
 #include "mozilla/Attributes.h"
+#include "mozilla/StyleBackendType.h"
 
 #include "nsChangeHint.h"
 #include "nsCOMPtr.h"
@@ -39,9 +40,29 @@ public:
   using base_type::Length;
   using base_type::operator[];
 
-  nsStyleChangeList() { MOZ_COUNT_CTOR(nsStyleChangeList); }
+  nsStyleChangeList(mozilla::StyleBackendType aType) :
+    mType(aType) { MOZ_COUNT_CTOR(nsStyleChangeList); }
   ~nsStyleChangeList() { MOZ_COUNT_DTOR(nsStyleChangeList); }
   void AppendChange(nsIFrame* aFrame, nsIContent* aContent, nsChangeHint aHint);
+
+  // Starting from the end of the list, removes all changes until the list is
+  // empty or an element with |mContent != aContent| is found.
+  void PopChangesForContent(nsIContent* aContent)
+  {
+    while (Length() > 0) {
+      if (LastElement().mContent == aContent) {
+        RemoveElementAt(Length() - 1);
+      } else {
+        break;
+      }
+    }
+  }
+
+  bool IsGecko() const { return mType == mozilla::StyleBackendType::Gecko; }
+  bool IsServo() const { return mType == mozilla::StyleBackendType::Servo; }
+
+private:
+  mozilla::StyleBackendType mType;
 };
 
 #endif /* nsStyleChangeList_h___ */

layout/generic/nsFrame.cpp

@@ -10087,6 +10087,11 @@ nsFrame::UpdateStyleOfChildAnonBox(nsIFrame* aChildFrame,
     &equalStructs,
     &samePointerStructs);
   if (childHint) {
+    if (childHint & nsChangeHint_ReconstructFrame) {
+      // If we generate a reconstruct here, remove any non-reconstruct hints we
+      // may have already generated for this content.
+      aChangeList.PopChangesForContent(aChildFrame->GetContent());
+    }
     aChangeList.AppendChange(aChildFrame, aChildFrame->GetContent(), childHint);
   }