Don't adjust for scrolling of the ancestor, rather than un-adjusting for it later.

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

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 89b23b078658cced2b4731d5f485539a9a6f9bb3..f4f1895ec1ec0bf281c1d1a3fdc39244fcd0c68e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -1013,12 +1013,13 @@ bool LayoutBox::mapScrollingContentsRectToBoxSpace(LayoutRect& rect, ApplyOverfl
     if (!hasOverflowClip())
         return true;
 
+    if (applyOverflowClip == ApplyNonScrollOverflowClip && scrollsOverflow()) {
+        return true;
+    }
+
     LayoutSize offset = LayoutSize(-scrolledContentOffset());
     rect.move(offset);
 
-    if (applyOverflowClip == ApplyNonScrollOverflowClip && scrollsOverflow())
-        return true;
-
     LayoutRect clipRect = overflowClipRect(LayoutPoint());
 
     bool doesIntersect;