For formats that can be loaded with data that has a different size pixel than
the internal format (UNSIGNED_INT -> GL_DEPTH_COMPONENT_24) the row length
would be computed as rowLength * 3 which is incorrect.

BUG=angleproject:1095

Change-Id: I0f60a3bb9bb387d475ddda1389a3b4b6f4973922
Reviewed-on: https://chromium-review.googlesource.com/360214Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>