Bug 1671527 Part 2 - Make ProcessChildren()'s callers responsible for calling MaybePushFloatContainingBlock(). r=emilio

Before this patch, a floating containing block (block frame)'s float
descendants are added to its mFloatedList in
~nsFrameConstructorSaveState() after returning from ProcessChildren().

This patch delays that by avoiding calling
MaybePushFloatContainingBlock() in ProcessChildren(), and move the call
one level up to ProcessChildren()'s callers so that the float
descendants are parented to the block frame after leaving the callers.
This is similar to how we handle the scope of abspos containing block.

This surely adds burden to some of the ProcessChildren() callers, but it
also unifies the float containing block scope for those callers
utilizing both ConstructFramesFromItemList() and ProcessChildren().

This doesn't change the behavior for now, but it is required by the next
part to correctly reparent the float descendants to the correct
non-column-span block continuations split by column-span wrappers.

Differential Revision: https://phabricator.services.mozilla.com/D120104

layout/base/nsCSSFrameConstructor.cpp

@@ -1968,6 +1968,10 @@ nsIFrame* nsCSSFrameConstructor::ConstructTable(nsFrameConstructorState& aState,
   if (display->IsAbsPosContainingBlock(newFrame)) {
     aState.PushAbsoluteContainingBlock(newFrame, newFrame, absoluteSaveState);
   }
+
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(innerFrame, floatSaveState);
+
   if (aItem.mFCData->mBits & FCDATA_USE_CHILD_ITEMS) {
     ConstructFramesFromItemList(
         aState, aItem.mChildItems, innerFrame,
@@ -2040,6 +2044,9 @@ nsIFrame* nsCSSFrameConstructor::ConstructTableRowOrRowGroup(
   MakeTablePartAbsoluteContainingBlockIfNeeded(aState, aDisplay,
                                                absoluteSaveState, newFrame);
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(newFrame, floatSaveState);
+
   nsFrameList childList;
   if (aItem.mFCData->mBits & FCDATA_USE_CHILD_ITEMS) {
     ConstructFramesFromItemList(
@@ -2136,14 +2143,11 @@ nsIFrame* nsCSSFrameConstructor::ConstructTableCell(
   MakeTablePartAbsoluteContainingBlockIfNeeded(aState, aDisplay,
                                                absoluteSaveState, newFrame);
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(cellInnerFrame, floatSaveState);
+
   nsFrameList childList;
   if (aItem.mFCData->mBits & FCDATA_USE_CHILD_ITEMS) {
-    // Need to push ourselves as a float containing block.
-    // XXXbz it might be nice to work on getting the parent
-    // FrameConstructionItem down into ProcessChildren and just making use of
-    // the push there, but that's a bit of work.
-    nsFrameConstructorSaveState floatSaveState;
-    aState.MaybePushFloatContainingBlock(cellInnerFrame, floatSaveState);
     ConstructFramesFromItemList(
         aState, aItem.mChildItems, cellInnerFrame,
         aItem.mFCData->mBits & FCDATA_IS_WRAPPER_ANON_BOX, childList);
@@ -2461,6 +2465,10 @@ nsIFrame* nsCSSFrameConstructor::ConstructDocElementFrame(
     NS_ASSERTION(!contentFrame->IsBlockFrameOrSubclass() &&
                      !contentFrame->IsFrameOfType(nsIFrame::eSVG),
                  "Only XUL frames should reach here");
+
+    nsFrameConstructorSaveState floatSaveState;
+    state.MaybePushFloatContainingBlock(contentFrame, floatSaveState);
+
     ProcessChildren(state, aDocElement, computedStyle, contentFrame, true,
                     childList, false);
 
@@ -3027,6 +3035,9 @@ void nsCSSFrameConstructor::InitializeSelectFrame(
     RestoreFrameStateFor(scrollFrame, aState.mFrameState);
   }
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(scrolledFrame, floatSaveState);
+
   // Process children
   nsFrameList childList;
 
@@ -3119,6 +3130,9 @@ nsIFrame* nsCSSFrameConstructor::ConstructFieldSetFrame(
                                        absoluteSaveState);
   }
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(contentFrame, floatSaveState);
+
   ProcessChildren(aState, content, computedStyle, contentFrame, true, childList,
                   true);
   nsFrameList fieldsetKids;
@@ -3805,10 +3819,10 @@ void nsCSSFrameConstructor::ConstructFrameFromItemInternal(
         }
       }
 
+      nsFrameConstructorSaveState floatSaveState;
+      aState.MaybePushFloatContainingBlock(newFrameAsContainer, floatSaveState);
+
       if (bits & FCDATA_USE_CHILD_ITEMS) {
-        nsFrameConstructorSaveState floatSaveState;
-        aState.MaybePushFloatContainingBlock(newFrameAsContainer,
-                                             floatSaveState);
         ConstructFramesFromItemList(
             aState, aItem.mChildItems, newFrameAsContainer,
             bits & FCDATA_IS_WRAPPER_ANON_BOX, childList);
@@ -4797,6 +4811,9 @@ nsContainerFrame* nsCSSFrameConstructor::ConstructFrameWithAnonymousChild(
                                                      aFrameList);
   }
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(innerFrame, floatSaveState);
+
   nsFrameList childList;
 
   // Process children
@@ -7928,6 +7945,9 @@ nsIFrame* nsCSSFrameConstructor::CreateContinuingTableFrame(
           state, headerFooterComputedStyle->StyleDisplay(), absoluteSaveState,
           headerFooterFrame);
 
+      nsFrameConstructorSaveState floatSaveState;
+      state.MaybePushFloatContainingBlock(headerFooterFrame, floatSaveState);
+
       ProcessChildren(state, headerFooter, rowGroupFrame->Style(),
                       headerFooterFrame, true, childList, false, nullptr);
       NS_ASSERTION(state.mFloatedList.IsEmpty(), "unexpected floated element");
@@ -9562,9 +9582,6 @@ void nsCSSFrameConstructor::ProcessChildren(
                                 &haveFirstLineStyle);
   }
 
-  nsFrameConstructorSaveState floatSaveState;
-  aState.MaybePushFloatContainingBlock(aFrame, floatSaveState);
-
   AutoFrameConstructionItemList itemsToConstruct(this);
 
   // If we have first-letter or first-line style then frames can get
@@ -10525,11 +10542,13 @@ void nsCSSFrameConstructor::ConstructBlock(
   nsFrameConstructorSaveState absoluteSaveState;
   (*aNewFrame)->AddStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
   if (aPositionedFrameForAbsPosContainer) {
-    //    NS_ASSERTION(aRelPos, "should have made area frame for this");
     aState.PushAbsoluteContainingBlock(
         *aNewFrame, aPositionedFrameForAbsPosContainer, absoluteSaveState);
   }
 
+  nsFrameConstructorSaveState floatSaveState;
+  aState.MaybePushFloatContainingBlock(blockFrame, floatSaveState);
+
   if (aParentFrame->HasAnyStateBits(NS_FRAME_HAS_MULTI_COLUMN_ANCESTOR) &&
       !ShouldSuppressColumnSpanDescendants(aParentFrame)) {
     blockFrame->AddStateBits(NS_FRAME_HAS_MULTI_COLUMN_ANCESTOR);
@@ -11670,6 +11689,10 @@ void nsCSSFrameConstructor::GenerateChildFrames(nsContainerFrame* aFrame) {
     nsAutoScriptBlocker scriptBlocker;
     nsFrameList childList;
     nsFrameConstructorState state(mPresShell, nullptr, nullptr, nullptr);
+
+    nsFrameConstructorSaveState floatSaveState;
+    state.MaybePushFloatContainingBlock(aFrame, floatSaveState);
+
     ProcessChildren(state, aFrame->GetContent(), aFrame->Style(), aFrame, false,
                     childList, false);