Bug 1209697: Clear ancestor intrinsic sizes when our block size changes

1 files changed, 6 insertions, 1 deletions

diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 2f12d62018..eab11b80c0 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -1634,9 +1634,14 @@ nsStylePosition::CalcDifference(const nsStylePosition& aNewData,
       // also have percentage bsizes. This is handled via
       // nsChangeHint_UpdateComputedBSize which clears intrinsic sizes
       // for frames that have such replaced elements.
+      //
+      // We need to use nsChangeHint_ClearAncestorIntrinsics for
+      // block-size changes so we clear results of cached CSS Flex
+      // measuring reflows.
       hint |= nsChangeHint_NeedReflow |
               nsChangeHint_UpdateComputedBSize |
-              nsChangeHint_ReflowChangesSizeOrPosition;
+              nsChangeHint_ReflowChangesSizeOrPosition |
+              nsChangeHint_ClearAncestorIntrinsics;
     }
 
     if (isVertical ? heightChanged : widthChanged) {