Update VE core submodule to master (859654b)

New changes:
6cb04e0 Fix JS error in mostly-dead Opera compat code
454d486 Handle triple click with surface fragments
c1e5c78 Update OOjs UI to v0.1.0-pre (afa3241e8e)
859654b Update OOjs UI to v0.1.0-pre (30b0407428)

Change-Id: I3f166c002783e9b62f31cbd0ef02930abe107b21