Detect a change in border that affects a positioned object's height or position

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index e9d007419042c786cccfc583a3b5e339e3730c45..a97898071c770c6226dac246dd3429e0053e196a 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -430,6 +430,7 @@ inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren, LayoutUnit &
     computeOverflow(oldClientAfterEdge);
 
     m_descendantsWithFloatsMarkedForLayout = false;
+    m_heightAvailableToChildrenChanged = false;

[mstensho (USE GERRIT), 2016/02/17 10:19:42]

So we'll only reset this flag for LayoutBlockFlow, and not for other LayoutBlock
types, such as LayoutTable and LayoutFlexibleBox.

m_widthAvailableToChildrenChanged has the same problem, though.

updateLogicalWidthAndColumnWidth(), which *may* call
widthAvailableToChildrenHasChanged(), which resets the flag.
updateLogicalWidthAndColumnWidth() is only called from LayoutBlockFlow and
LayoutFlexibleBox, but the flag is never reset if oldWidth != logicalWidth() in
updateLogicalWidthAndColumnWidth().

We should probably clean up this, but that's for a different CL. Could you add a
TODO here, though?

     return true;
 }