2013-05-17  Sharath Kamath  <s.kamath@samsung.com>

        WebCL must create a default context without any shared context.
        Issue #234

        Reviewed by Antonio.

        Use NoSharedGLContext instead when user wants a default context.
        This will fix all calls to createContext() API without ContextProperties.
        Thus fixing basic Hello Demo.

        No new tests (OOPS!).

        * Modules/webcl/WebCL.cpp:
        (WebCore::WebCL::defaultProperties):