Reland with a fix for the compilation on Windows.
Rereland with a fix for the Chromium compilation on Windowds.

Our angle_config.h was using "using namespace" in a header as a way to
import symbols to shim Chromium's base. This patch changes this to
import each function separately using "using".

This patch will allow our gpu_test_expectations to compile inside
Chromium on Linux.

BUG=angleproject:1127

Change-Id: Iefb9e253e278fa766a11e50fc6a69eceb2e81dd9
Reviewed-on: https://chromium-review.googlesource.com/295192Tested-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>