This makes it easier to allocate char arrays in the memory pool.

TEST=angle_unittests
BUG=angleproject:2267

Change-Id: I1673330f58968ea9d38c671b70a7a489276af863
Reviewed-on: https://chromium-review.googlesource.com/883805Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>