Use float for scroll offset.

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 426fe4ed246d2aa856b7670cefd607aa00f5b979..923e46615877c2bc8aaa959a68fb91ce345ef578 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.h
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.h
@@ -551,9 +551,9 @@ class CORE_EXPORT LayoutBox : public LayoutBoxModelObject {
   virtual void setScrollLeft(LayoutUnit);
   virtual void setScrollTop(LayoutUnit);
 
-  void scrollToOffset(const DoubleSize&,
-                      ScrollBehavior = ScrollBehaviorInstant);
-  void scrollByRecursively(const DoubleSize& delta);
+  void scrollToPosition(const FloatPoint&,
+                        ScrollBehavior = ScrollBehaviorInstant);
+  void scrollByRecursively(const ScrollOffset& delta);
   // If makeVisibleInVisualViewport is set, the visual viewport will be scrolled
   // if required to make the rect visible.
   void scrollRectToVisible(const LayoutRect&,