Fix linkage.html failures on Mac. The failure is due to when we initialize variables to 0, we re-create the struct TType, and it contains a different unique id from the original struct TType, thus leading to a different hashed name. BUG=chromium:641129 TEST=webgl_conformance,webgl2_conformance Change-Id: I267b97fa496f55ea59dacee93af8f6a90f3e66cb Reviewed-on: https://chromium-review.googlesource.com/409602 Commit-Queue: Zhenyao Mo <zmo@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>