Rework mapToVisualRectInAncestorSpace to handle flipped blocks correctly.

third_party/WebKit/Source/core/layout/LayoutBox.h

Index: third_party/WebKit/Source/core/layout/LayoutBox.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.h b/third_party/WebKit/Source/core/layout/LayoutBox.h
index ca52d258eeabb66f7353e856939b932881e1c417..1c0d2d82b1b5c9d9e5ca3ae7815127cb84f12ae7 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.h
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.h
@@ -875,7 +875,7 @@ public:
     }
     // These represent your location relative to your container as a physical offset.
     // In layout related methods you almost always want the logical location (e.g. x() and y()).
-    LayoutPoint topLeftLocation() const;
+    LayoutPoint topLeftLocation(const LayoutBox* container = nullptr) const;

[chrishtr, 2016/07/09 00:15:57]

Add a comment saying that passing |container| causes flipped-block flipping
w.r.t. that container, or containingBlock() otherwise.

Also rename the arg to flippedBlocksContainer.

[wkorman, 2016/07/09 01:16:08]

Done.

     LayoutSize topLeftLocationOffset() const { return toLayoutSize(topLeftLocation()); }
 
     LayoutRect logicalVisualOverflowRectForPropagation(const ComputedStyle&) const;