From the GLES3 spec:
"... When a program object's LINK_STATUS is FALSE, its program binary
length is zero ..."

Querying the size was generating errors in the GL backend.

BUG=angleproject:2569

Change-Id: I1be511040331abaec2bba98502d8aa88fb4bd19c
Reviewed-on: https://chromium-review.googlesource.com/1076317
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>