Implement the WebGL VertexAttribPointer restrictions BUG=angleproject:1523 BUG=chromium:668223 Change-Id: Ic89c476a6c95824069772e22ede596ba85ac8859 Reviewed-on: https://chromium-review.googlesource.com/422347 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>