Store multiple vertex executables in the program binary. With dynamic vertex conversion the GPU, we will have different input layouts resulting in different executables. This patch adds a way of mapping the input layouts to vertex executables. BUG=angle:560 Change-Id: Ie36f2f8ac2dfcb96f562af577d31f57d6d89b447 Reviewed-on: https://chromium-review.googlesource.com/185192 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>