The parser would become confused over the purported array size
of struct indexes. In reality they were always a single direct
index into a struct, but it would take the object size of the
represented type (EG, a vec4 would have size 4) and deference
out-of-bounds memory.

BUG=434033

Change-Id: I92349aa04e6faadc766cb28c04e28d5f19c4e1ec
Reviewed-on: https://chromium-review.googlesource.com/230530Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>