Reviewed by Adam Barth.

        Persist V8's ScriptData to the memory cache.
        https://bugs.webkit.org/show_bug.cgi?id=38661

        This stores V8's ScriptData in the memory cache and also causes the
        network platform layer to be notified of the available cacheable
        metadata.

        Chromium's morejs benchmark shows a 3-4% improvement on fast hardware.

        No new tests because no new functionality.

        * bindings/v8/ScriptSourceCode.h:
        (WebCore::ScriptSourceCode::ScriptSourceCode):
        (WebCore::ScriptSourceCode::cachedScript):
        * bindings/v8/V8Proxy.cpp:
        (WebCore::V8Proxy::compileScript):
        (WebCore::V8Proxy::precompileScript):
        (WebCore::V8Proxy::evaluate):
        * bindings/v8/V8Proxy.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@60684 268f45cc-cd09-0410-ab3c-d52691b4dbfc