When getUniformInternal detected a mismatch between the glGetUniform
type and the uniform type, it entered a code path where it wrongly wrote
the whole array instead of a single element, causing a buffer overflow.

Adds a regression test.

BUG=595836

Change-Id: Id7372faece276d28363a30bf3183497d97357c76
Reviewed-on: https://chromium-review.googlesource.com/333771Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>