<rdar://problem/6474973> REGRESSION: PLT ~2% slower due to 39465 (consolidate thread data)

        I could not reproduce the slowdown on my PowerPC test machine, but the change should bring
        performance back.

        * platform/ThreadGlobalData.cpp: (WebCore::threadGlobalData): Don't use AtomicallyInitializedStatic.
        Prior to r39465, it was only used for cached converters, which was necessary because the
        first access to ICU or TEC one could happen on a secondary thread, but now they are all
        initialized from ThreadGlobalData constructor.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@39656 268f45cc-cd09-0410-ab3c-d52691b4dbfc