[GTK][WK2] Add WebGL WebSetting.

[GTK][WK2] Add WebGL WebSetting.
https://bugs.webkit.org/show_bug.cgi?id=79217

Patch by Antaryami Pandia <antaryami.pandia@motorola.com> on 2012-02-22
Reviewed by Martin Robinson.

Add a WebSetting to enable/disable Webgl.

* UIProcess/API/gtk/WebKitSettings.cpp:
(webKitSettingsSetProperty):
(webKitSettingsGetProperty):
(webkit_settings_class_init):
(webkit_settings_set_enable_webaudio):
(webkit_settings_get_enable_webgl):
(webkit_settings_set_enable_webgl):
* UIProcess/API/gtk/WebKitSettings.h:
* UIProcess/API/gtk/docs/webkit2gtk-sections.txt:
* UIProcess/API/gtk/tests/TestWebKitSettings.cpp:
(testWebKitSettings):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108512 268f45cc-cd09-0410-ab3c-d52691b4dbfc