Use float for scroll offset.

third_party/WebKit/Source/core/frame/DOMVisualViewport.h

Index: third_party/WebKit/Source/core/frame/DOMVisualViewport.h
diff --git a/third_party/WebKit/Source/core/frame/DOMVisualViewport.h b/third_party/WebKit/Source/core/frame/DOMVisualViewport.h
index 6f27bb9fb73f7e0d53b9a18534cf28a17060926c..4a7d3af6b7b646db33d5f4f48e86e50873850665 100644
--- a/third_party/WebKit/Source/core/frame/DOMVisualViewport.h
+++ b/third_party/WebKit/Source/core/frame/DOMVisualViewport.h
@@ -35,6 +35,7 @@
 #include "core/dom/ExecutionContext.h"
 #include "core/events/EventTarget.h"
 #include "platform/heap/Handle.h"
+#include "platform/scroll/ScrollTypes.h"
 
 namespace blink {
 
@@ -57,10 +58,10 @@ class DOMVisualViewport final : public EventTargetWithInlineData {
   const AtomicString& interfaceName() const override;
   ExecutionContext* getExecutionContext() const override;
 
-  double scrollLeft();
-  double scrollTop();
-  double pageX();
-  double pageY();
+  ScrollUnit scrollLeft();
+  ScrollUnit scrollTop();
+  ScrollUnit pageX();
+  ScrollUnit pageY();
   double clientWidth();
   double clientHeight();
   double scale();