Fix event passing to overlay scrollbars when over a plugin

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index 46e48ac448b53e0de8c14b10db360fc897fd2c5e..7c91f6bd48f327730e2ffb8f7bc54a8d8c9926ff 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -1271,6 +1271,14 @@ bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
 
     m_frame->selection().setCaretBlinkingSuspended(true);
 
+    FrameView* view = m_frame->view();
+    Scrollbar* scrollbar = view ? view->scrollbarAtPoint(mouseEvent.position()) : 0;

[Rick Byers, 2014/05/22 13:53:36]

Shouldn't this already be in mev.scrollbar()?  Seems wrong to hit test this
special case again when we already have a HitTestResults here.

+    if (scrollbar) {
+        updateLastScrollbarUnderMouse(scrollbar, true);
+        if (passMousePressEventToScrollbar(mev, scrollbar))
+            return true;
+    }
+
     bool swallowEvent = !dispatchMouseEvent(EventTypeNames::mousedown, mev.targetNode(), m_clickCount, mouseEvent, true);
     swallowEvent = swallowEvent || !handleMouseFocus(mouseEvent);
     m_capturesDragging = !swallowEvent || mev.scrollbar();
@@ -1287,7 +1295,7 @@ bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
 
     if (swallowEvent) {
         // scrollbars should get events anyway, even disabled controls might be scrollable
-        Scrollbar* scrollbar = mev.scrollbar();
+        scrollbar = mev.scrollbar();
 
         updateLastScrollbarUnderMouse(scrollbar, true);
 
@@ -1299,10 +1307,7 @@ bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
             mev = m_frame->document()->prepareMouseEvent(request, documentPoint, mouseEvent);
         }
 
-        FrameView* view = m_frame->view();
-        Scrollbar* scrollbar = view ? view->scrollbarAtPoint(mouseEvent.position()) : 0;
-        if (!scrollbar)
-            scrollbar = mev.scrollbar();
+        scrollbar = mev.scrollbar();
 
         updateLastScrollbarUnderMouse(scrollbar, true);