Remove dm.Surface's 'change' event

ve.dm.Surface.js:
* Stop emitting 'change' and remove its event documentation

ve.ce.Surface.js:
* Listen to 'select' instead of 'change'
* Perform a CE surface update after model-based keydown handling

ve.dm.Surface.test.js:
* Stop asserting that 'change' is emitted

Change-Id: I8f16289493e835d890709c6dfe093d04c18522b6
Enslave dm.Surface to dm.Document

* Replace surface 'transact' event with 'documentUpdate' event
* Have surface listen for all document transactions and update selection
  as appropriate (as well as emitting 'documentUpdate')
* Implement change() in terms of setSelection()
** Queue 'contextChange' events so contextChange is only emitted once
** Use this.transacting flag to prevent setSelection() (which is called
   because the model emits transact events) from doing too much
** Behavioral change: lock/unlock now emitted separately for
   transaction and selection changes

Change-Id: I44425d260ec70758f99d13f99e41f5c993d260c2
Implement ve.dm.Surface.prototype.undo() and redo() in terms of change()

...or really changeInternal(), so we can avoid adding undo transactions
to the undo stack.

Also get rid of the pattern where undo() and redo() return a selection
which the caller then has to restore, and instead just restore the
selection.

Bug: 53224
Change-Id: If5a3b4d4162e9f0713ee9cd26e79a66efe52770f
Remove SurfaceObserver locking (unused)

The SurfaceObserver lock guarded against setTimeout calls, but the lock
was only ever used synchronously.

Remove 'lock' and 'unlock' events. Instead, re-sync the SurfaceObserver
by listening to the 'documentUpdate' and 'select' events.

Signed-off-by: Roan Kattouw <roan.kattouw@gmail.com>
Change-Id: Ib15c39f3d25677da70625581b3b2765ae66994b4
.change( null, foo ) -> .setSelection( foo )

Change-Id: Iaba76ac17888a7825f5a9cd1c383d4f429454278
Merge changes Iaba76ac1,Ib15c39f3,If5a3b4d4,I44425d26,I8f162894

* changes:
  .change( null, foo ) -> .setSelection( foo )
  Remove SurfaceObserver locking (unused)
  Implement ve.dm.Surface.prototype.undo() and redo() in terms of change()
  Enslave dm.Surface to dm.Document
  Remove dm.Surface's 'change' event