2014-01-21 Sharath Kamath <s.kamath@samsung.com>

Enable WEBCL_html_image extension.

Issue #414

Reviewed by Antonio.

Conformance test cases:
[https://github.com/SRA-SiliconValley/webkit-webcl-conformance]
All test cases under "WEBCL_html_image" extension.

* Modules/webcl/WebCLExtensionsAccessor.cpp:
(WebCore::::enableExtension):
(WebCore::::getSupportedExtensions):
readme