[QtScript/JavaScriptCore] Expose function parameter names

Patch: http://gitorious.org/+qtwebkit-developers/qtwebkit/qtwebkit-qtscript-integration/commit/8d336de7ba8eff1a3842a17fdc02eb0b216e9dcb

Needed to implement QScriptContextInfo.
Patch can't be upstreamed as-is, since there is no code upstream that would call it.
Can be worked around easily by calling paramString() and splitting the result on ", ".

Proposed action: Work around as suggested (it's not performance-critical code anyway), and drop the patch.