Reviewed by Darin Fisher.

        Adding EventListeners to the chromium API.

        https://bugs.webkit.org/show_bug.cgi?id=33882

        * WebKit.gyp:
        * public/WebEvent.h: Added.
        * public/WebEventListener.h: Added.
        * public/WebMutationEvent.h: Added.
        * public/WebNode.h:
        * public/WebString.h:
        (WebKit::operator==):
        (WebKit::operator!=):
        * src/EventListenerWrapper.cpp: Added.
        * src/EventListenerWrapper.h: Added.
        * src/WebEvent.cpp: Added.
        * src/WebEventListener.cpp: Added.
        * src/WebEventListenerPrivate.cpp: Added.
        * src/WebEventListenerPrivate.h: Added.
        * src/WebNode.cpp:
        (WebKit::WebNode::addEventListener):
        (WebKit::WebNode::removeEventListener):
        * src/WebString.cpp:
        (WebKit::WebString::equals):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@53934 268f45cc-cd09-0410-ab3c-d52691b4dbfc