- js/CallAndConstruct.h: Now contains JS::Call, JS::Construct, and
  related
- js/Debug.h: Already existed, but now contains JS_DefineDebuggerObject
- js/GlobalObject.h: Now contains JS::CurrentGlobalOrNull
- js/PropertyAndElement.h: Now contains APIs for getting, setting, and
  defining properties, as well as array elements
- js/ScriptPrivate.h: Now contains JS::GetScriptPrivate/SetScriptPrivate
- js/Stack.h: Now contains APIs that have to do with the call stack