This method is unavailable due to being c++11.

BUG=angle:773

Change-Id: I995e03c26b5d3103fab963d8fb1eddc5050cf5b5
Reviewed-on: https://chromium-review.googlesource.com/240096Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>