Re-enable context-attribute-preserve-drawing-buffer.html on mac.

We could probably re-enable the test on win intel, but I'd like to do it separately just in case.

BUG=322770
TEST=mac gpu bots
TBR=kbr@chromium.org

Review URL: https://codereview.chromium.org/153473005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249664 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249664
Implement ui for re-parenting an item from an app list folder to another position or folder in the top level data model item list.

This cl implement the following features:

1. When an item is dragged inside a folder, an ink bubble will show to indicate whether the item is dragged within the folder(reorder within the folder), or dragged out of the folder.

2. If the item is dragged out of the folder, the folder view UI will transit back to top level apps grid view, the dragged item will be removed from its parent folder and reparented to:
(1). Another position in the top level item list, if user drops it to another position in the top level grid view.
(2). Another folder in the top level item list, if user drops it to another item or folder in the top level grid view.
(3). Go back its original parent folder, if user release the mouse without dropping it to a valid target.

3. Enable drag/drop a item inside a folder to the shelf.

BUG=308765

Review URL: https://codereview.chromium.org/136303008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249665 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249665