2013-03-05  Sharath Kamath  <kamath.sharath@gmail.com>

        Part 1 - WebCL API must throw meaning full Exceptions.
        Issue #123

        Reviewed by NOBODY (OOPS!).

        Refactor WebCLCommandQueue.cpp.
        Check exceptions thrown and also add null checks when pointer
        are dereferenced.

        No new tests.

        * Modules/webcl/WebCLCommandQueue.cpp:
        (WebCore::WebCLCommandQueue::getInfo):
        (WebCore::WebCLCommandQueue::enqueueWriteBufferBase):
        (WebCore::WebCLCommandQueue::enqueueWriteBuffer):
        (WebCore::WebCLCommandQueue::enqueueWriteBufferRect):
        (WebCore::WebCLCommandQueue::enqueueReadBuffer):
        (WebCore::WebCLCommandQueue::enqueueReadImage):
        (WebCore::WebCLCommandQueue::enqueueReadBufferRect):
        (WebCore::WebCLCommandQueue::enqueueNDRangeKernel):
        (WebCore::WebCLCommandQueue::finish):
        (WebCore::WebCLCommandQueue::flush):
        (WebCore::WebCLCommandQueue::enqueueWriteImage):
        (WebCore::WebCLCommandQueue::enqueueAcquireGLObjects):
        (WebCore::WebCLCommandQueue::enqueueReleaseGLObjects):
        (WebCore::WebCLCommandQueue::enqueueCopyImage):
        (WebCore::WebCLCommandQueue::enqueueCopyImageToBuffer):
        (WebCore::WebCLCommandQueue::enqueueCopyBufferToImage):
        (WebCore::WebCLCommandQueue::enqueueCopyBuffer):
        (WebCore::WebCLCommandQueue::enqueueCopyBufferRect):
        (WebCore::WebCLCommandQueue::enqueueBarrier):
        (WebCore::WebCLCommandQueue::enqueueTask):