This patch will remove unused functions syncVertexAttributes and
hasDirtyOrDynamicAttrib, and private member mAppliedIBChanged.
Meanwhile, it changes hasDynamicAttrib to hasActiveDynamicAttrib
to avoid unnecessary update in some cases.

BUG=angleproject:1155

Change-Id: I29a0aa7fbc13874b7b070cf1ac5ec4134728f519
Reviewed-on: https://chromium-review.googlesource.com/707014Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>