Only hide popups on selection change

Hiding on attribute change would prevent us having inspectors
which live-update their nodes.

Change-Id: If1250402f266772c3db1317d880a603068e70ba4
Create ve#contains

A slightly more useful version of jQuery#contains.

Change-Id: I7ed4eef7e1f5ad38e1d31939d04dd411855166a2
Prevent pasteTarget selection while already selected

onModelSelect is used to restore focusable node selections when a
dialog is closed, but the logical refactoring to do this was overly
generous in that this.focusedNode was allowed to clear, and the
pasteTarget was re-focused, emitting extra unhelpful events.

Change-Id: I466a64364fa5c38f177354b28ebfad02fb9df1a0
Make ve.dm.Surface#breakpoint not crash

Change-Id: Idf83edfca411881c8998129205984c2d5299e804