Notify the VertexArrayImpl when a buffer is detached. Update VertexArrayGL to clear it's cached buffer binding when a buffer is detached to prevent name aliasing. Fixes: * DEQP standalone crashes. * WebGL Conformance DEQP tests. Change-Id: If21a617629e15873ddeae0368b5399616f2ca68b Reviewed-on: https://chromium-review.googlesource.com/278050 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>