With this change, the common sources shared between translator
and translator_static are compiled in a static library. There
is only one file with exported functions which needs to be
compiled for each target. This should reduce ANGLE and chromium
build times.

BUG=angle:569

Change-Id: I3ce011872323ec988befbd6db731add4fce5787b
Reviewed-on: https://chromium-review.googlesource.com/197021Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>