Improve drag-and-drop comment in MouseEventManager.

third_party/WebKit/Source/core/input/MouseEventManager.cpp

Index: third_party/WebKit/Source/core/input/MouseEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/MouseEventManager.cpp b/third_party/WebKit/Source/core/input/MouseEventManager.cpp
index d377ff2b423022d1734cdc75bcfb814c27e0beca..da2fdc0a8a78bdcbc0a56a3daa86e3d5103e630e 100644
--- a/third_party/WebKit/Source/core/input/MouseEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/MouseEventManager.cpp
@@ -901,8 +901,7 @@ void MouseEventManager::dragSourceEndedAt(const PlatformMouseEvent& event,
                                           DragOperation operation) {
   if (dragState().m_dragSrc) {
     dragState().m_dragDataTransfer->setDestinationOperation(operation);
-    // For now we don't care if event handler cancels default behavior, since
-    // there is none.
+    // The return value is ignored because dragend is not cancelable.
     dispatchDragSrcEvent(EventTypeNames::dragend, event);
   }
   clearDragDataTransfer();