This patch adds entrypoints glMultiDrawArraysANGLE,
glMultiDrawElementsANGLE, glMultiDrawArraysInstancedANGLE,
annd glMultiDrawElementsInstancedANGLE

Bug: chromium:890539

Change-Id: Ic9c374c53892460f44ca6e73a253b78473ac2dff
Reviewed-on: https://chromium-review.googlesource.com/c/1282268Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>