Call JS_AddExtraGCRootsTracer and JS_RemoveExtraGCRootsTracer depending
on JS::Heap use instead of on CGUI page link setup.
GUIObjects should be able to access the GUI page independent of the
scripting (for example to obtain PredefinedColors, refs D2108).
Refs: D2108, c02a7e1a7b
Comments By: wraitii
This was SVN commit r22587.