Use float for scroll offset.

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

 /*
  * Copyright (C) 2016 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef DOMVisualViewport_h
 #define DOMVisualViewport_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/events/EventTarget.h"
 #include "platform/heap/Handle.h"
+#include "platform/scroll/ScrollTypes.h"
 
 namespace blink {
 
 class LocalDOMWindow;
 class ExecutionContext;
 
 class DOMVisualViewport final : public EventTargetWithInlineData {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static DOMVisualViewport* create(LocalDOMWindow* window) {
     return new DOMVisualViewport(window);
   }
 
   ~DOMVisualViewport() override;
 
   DECLARE_VIRTUAL_TRACE();
 
   // EventTarget overrides:
   const AtomicString& interfaceName() const override;
   ExecutionContext* getExecutionContext() const override;
 
-  double scrollLeft();
-  double scrollTop();
-  double pageX();
-  double pageY();
+  float scrollLeft();
+  float scrollTop();
+  float pageX();
+  float pageY();
   double clientWidth();
   double clientHeight();
   double scale();
 
  private:
   explicit DOMVisualViewport(LocalDOMWindow*);
 
   Member<LocalDOMWindow> m_window;
 };
 
 }  // namespace blink
 
 #endif  // DOMVisualViewport_h