[MD Bookmarks] Clear drop indicator when dragging over invalid target.

chrome/test/data/webui/md_bookmarks/dnd_manager_test.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 suite('drag and drop', function() {
   var app;
   var list;
   var rootFolderNode;
   var store;
   var dndManager;
@@ skipping 131 matching lines @@
     dispatchDragEvent('dragover', dragTarget);
     assertEquals(
         DropPosition.ON | DropPosition.ABOVE | DropPosition.BELOW,
         dndManager.calculateValidDropPositions_(dragTarget));
     assertDragStyle(dragTarget, DRAG_STYLE.ON);
 
     // There are no valid drop locations for dragging an item onto itself.
     assertEquals(
         DropPosition.NONE,
         dndManager.calculateValidDropPositions_(dragElement));
-    dispatchDragEvent('dragleave', dragTarget);
     dispatchDragEvent('dragover', dragElement);
 
     assertDragStyle(dragTarget, DRAG_STYLE.NONE);
     assertDragStyle(dragElement, DRAG_STYLE.NONE);
   });
 
   test('reorder folder nodes', function() {
     var dragElement = getFolderNode('112');
     var dragTarget = getFolderNode('111');
     dispatchDragEvent('dragstart', dragElement);
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     assertDeepEquals(['14'], normalizeSet(store.data.selection.items));
     dispatchDragEvent('dragend', dragElement);
 
     // Dragging a folder node deselects any selected items in the bookmark list.
     dragElement = getFolderNode('15');
     dispatchDragEvent('dragstart', dragElement);
     assertDeepEquals([], normalizeSet(store.data.selection.items));
     dispatchDragEvent('dragend', dragElement);
   });
 });