Don't dispatch a 'click' event for mousedown/mouseup across form controls.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 1594 matching lines @@
 
     return swallowEvent;
 }
 
 void EventHandler::invalidateClick()
 {
     m_clickCount = 0;
     m_clickNode = 0;
 }
 
+static Node* parentForClickEvent(const Node& node)
+{
+    // IE doesn't dispatch click events for mousedown/mouseup events across form
+    // controls.
+    if (node.isHTMLElement() && toHTMLElement(node).isInteractiveContent())
+        return 0;
+    return node.parentOrShadowHostNode();
+}
+
 bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
 {
     RefPtr<FrameView> protector(m_frame->view());
 
     m_frame->selection().setCaretBlinkingSuspended(false);
 
     bool defaultPrevented = dispatchSyntheticTouchEventIfEnabled(mouseEvent);
     if (defaultPrevented)
         return true;
 
@@ skipping 44 matching lines @@
 
     bool contextMenuEvent = mouseEvent.button() == RightButton;
 #if OS(MACOSX)
     // FIXME: The Mac port achieves the same behavior by checking whether the context menu is currently open in WebPage::mouseEvent(). Consider merging the implementations.
     if (mouseEvent.button() == LeftButton && mouseEvent.modifiers() & PlatformEvent::CtrlKey)
         contextMenuEvent = true;
 #endif
 
     bool swallowClickEvent = false;
     if (m_clickCount > 0 && !contextMenuEvent && mev.targetNode() && m_clickNode) {
-        if (Node* clickTargetNode = mev.targetNode()->commonAncestorOverShadowBoundary(*m_clickNode))
+        if (Node* clickTargetNode = mev.targetNode()->commonAncestor(*m_clickNode, parentForClickEvent))
             swallowClickEvent = !dispatchMouseEvent(EventTypeNames::click, clickTargetNode, true, m_clickCount, mouseEvent, true);
     }
 
     if (m_resizeScrollableArea) {
         m_resizeScrollableArea->setInResizeMode(false);
         m_resizeScrollableArea = 0;
     }
 
     bool swallowMouseReleaseEvent = false;
     if (!swallowMouseUpEvent)
@@ skipping 2318 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore