WebCL Conformance test suite update for review.

    Fixes the below issues ::
    [Khronos #53] Add testcase to ensure that kernel name is not more than 256 characters.
    [Khronos #55] Refactor cl_commandQueue_enqueueMarker.html to throw INVALID_EVENT on taking webCLUserEvent as input.

    Add testcase for WebCLKernel::setArg(index, <64bit-integer>) support.
    Add testcase for async variant of WebCLCommandQueue::finish
    Add functionality tests for createBuffer API.
    Fix Non-blocking enqueueRead* API's crash occasionally.
    Add testcase to verify INVALID_EVENT in cl_event_getinfo.html and cl_event_getProfilingInfo.html
    Validate ArrayBufferView types against type in Kernel signature to check for INVALID_ARG_VALUE in setArg
    Add testcases to verify exception for WebCLBuffer :: createSubBuffer
    Releasing resources at end of test case.

    Enable extension for create{Buffer, Image}Validation in WEBCL_html_image extn.
    Add testcases to verify valid param values for enqueue APIs in extn WEBCL_html_image.
    Releasing context and creating a new one, after enabling extension WEBCL_html_image.
    Relax test of MEM_OBJECT_IMAGE3D in cl_webcl_constants_check.html

    Adding testcases for enqueueAcquireGLObjects API in extension: KHR_gl_sharing.
    Adding testcases for enqueueReleaseGLObjects API in extension: KHR_gl_sharing.
    Route all gl & clgl calls via WebCLGLUtils
    Moving CLGL constants check before enabling extension, to KHR_gl_sharing folder.
    Using shouldBeValueOrUndefined for extension enums which can be optionally visible without enabling the extension.

    Contributors :
    SRI-B : Shilpa Shri, Sharath Kamath, Gajendra N.
    SRA : Antonio Gomes and Steven Eliuk.