Bug 903569.  Remove the unneeded CheckPropertyAccess call in the GSP.  r=bholley,peterv
Bug 917539.  Move the JSCompartment argument to the end of the list for JS-implemented WebIDL, so C++ callers can call into it sanely too.  r=peterv
Bug 917958 part 1.  Stop using JSObject* to represent WebIDL callback functions in workers.  r=smaug
Bug 917958 part 2.  Simplify our various typeNeedsCx stuff, now that it's the same on workers and mainthread.  r=smaug