This will allow us to use these methods when compiling the translator
as a DLL.

BUG=angle:466,697

Change-Id: Ic9169fb7c69fe0bf5f98addfc128a30ee6b2159d
Reviewed-on: https://chromium-review.googlesource.com/208752Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>