2013-12-27 Sharath Kamath <s.kamath@samsung.com>
        Implement "Writing to WebCLImage" section.

        Issue #384

        Reviewed by Antonio.

        Implement WEBCL_HTML_image extension 'Writing to WebCLImage' section.
        This will support enqueueWriteImage API with Canvas, image and ImageData.
        Also add a generic API enqueueWriteImageBase() acting like a base function
        for all enqueueWriteImage API's.

        Conformance test cases:
        [https://github.com/SRA-SiliconValley/webkit-webcl-conformance
        conformance/extension/WEBCL_html_image/cl_commandQueue_enqueueWriteImage_*.html

        * Modules/webcl/WebCLCommandQueue.cpp:
        (WebCore::WebCLCommandQueue::enqueueWriteImageBase):
        (WebCore::WebCLCommandQueue::enqueueWriteImage):
        * Modules/webcl/WebCLCommandQueue.h:
        * Modules/webcl/WebCLCommandQueue.idl:
update read me