Prevent default actions for JS-generated mouse events other than click

Source/core/dom/Node.h

Index: Source/core/dom/Node.h
diff --git a/Source/core/dom/Node.h b/Source/core/dom/Node.h
index 7e6bc65f550156a0dba0a749d03d767fd02aa7d8..d4841e0f3499f29ca2a2cb89fef72ac62cd48612 100644
--- a/Source/core/dom/Node.h
+++ b/Source/core/dom/Node.h
@@ -62,6 +62,7 @@ class HTMLInputElement;
 class HTMLQualifiedName;
 class IntRect;
 class KeyboardEvent;
+class MouseEvent;
 class NSResolver;
 class NameNodeList;
 class NamedNodeMap;
@@ -638,6 +639,7 @@ public:
     virtual void postDispatchEventHandler(Event*, void* /*dataFromPreDispatch*/) { }
 
     using EventTarget::dispatchEvent;
+    // This dispatchEvent override is intended to only be used for events dispatched from script
     virtual bool dispatchEvent(PassRefPtrWillBeRawPtr<Event>) override;
 
     void dispatchScopedEvent(PassRefPtrWillBeRawPtr<Event>);
@@ -651,6 +653,7 @@ public:
     bool dispatchKeyEvent(const PlatformKeyboardEvent&);
     bool dispatchWheelEvent(const PlatformWheelEvent&);
     bool dispatchMouseEvent(const PlatformMouseEvent&, const AtomicString& eventType, int clickCount = 0, Node* relatedTarget = nullptr);
+    bool dispatchMouseEvent(PassRefPtrWillBeRawPtr<MouseEvent>);
     bool dispatchGestureEvent(const PlatformGestureEvent&);
     bool dispatchTouchEvent(PassRefPtrWillBeRawPtr<TouchEvent>);