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This CL removes GTEST_LANG_CXX11=0 from build configuration, and let
gtest detect whether C++11 is available. And to make it work, this CL
injects a custom gmock-port.h to provide missing type_traits.

BUG=630299

Review-Url: https://codereview.chromium.org/2174663002
Cr-Commit-Position: refs/heads/master@{#407360}