Fixed memory leak associated with TLS. We used to allocate thread-local memory on each compile. If the compile did not happen on the same thread as ShInitialize, we leaked the thread-local memory. It turns out that there is no need to allocate any thread-local memory. This patch cleans up all the unnecessary junk around TLS. BUG=crbug.com/181691 R=kbr@chromium.org Review URL: https://codereview.appspot.com/11679046 Conflicts: src/compiler/ConstantUnion.h src/compiler/ShaderLang.cpp src/compiler/Types.h src/compiler/ValidateLimitations.cpp