We can use the same code for this method, with the only difference
being in when we determine a texture image holds no pixels.

BUG=angle:729

Change-Id: I3356f5deb900c24b1a5c739ce8de99e9ce1371c0
Reviewed-on: https://chromium-review.googlesource.com/219861Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>