Add "targetViewport" to ScrollBegin and FlingStart

public/web/WebInputEvent.h

Index: public/web/WebInputEvent.h
diff --git a/public/web/WebInputEvent.h b/public/web/WebInputEvent.h
index 6945f4ce63aaace89dd1b63b538312ac1c13e04e..50ed2a36855fc334d060bd5169e4c931cad09d6f 100644
--- a/public/web/WebInputEvent.h
+++ b/public/web/WebInputEvent.h
@@ -469,6 +469,8 @@ public:
             // May be redundant with deltaX/deltaY in the first scrollUpdate.
             float deltaXHint;
             float deltaYHint;
+            // True if the scroll is targeted to viewport.

[bokan, 2015/06/16 14:38:04]

I would make the comment more explicit that we'll skip hit testing. Something
along the lines of: "If true, this event will skip hit testing to find a scroll
target and, instead, scroll the viewport."

[hush (inactive), 2015/06/18 20:25:48]

Done.

+            bool targetViewport;
         } scrollBegin;
 
         struct {
@@ -489,6 +491,8 @@ public:
         struct {
             float velocityX;
             float velocityY;
+            // True if the fling is targeted to viewport.
+            bool targetViewport;
         } flingStart;
 
         struct {