This validates all necessary buffer sizes for element array
buffers in the validation layer, before we start the draw.

BUG=angle:571

Change-Id: I602744ca1ea493e9f0f7e1ccbeb85fc4ae5c9f5a
Reviewed-on: https://chromium-review.googlesource.com/210648Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>