This bug was crashing the IncompleteTextureTest in Release mode.
Fix this by releasing the textures before we free the D3D11
libraries.

BUG=angle:838

Change-Id: I771e4cc6876e3529c5d26f36711dea9181e631f0
Reviewed-on: https://chromium-review.googlesource.com/231247Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>