Bug 860897 - Add locale to stub installer fallback url. r=bbondy, a=akeybl
Bug 865948 - Return the appropriate value when the whitelist checks fail. r=gabor, a=bajaj
Bug 861493 - When passing arguments to an Xray for a WebIDL constructor, make sure to do the argument unwrapping before entering the content compartment. r=bholley, r=Waldo, a=akeybl

There are several changes here:

1) Adds some MutableThis methods to Optional, Nullable, and dictionaries to
   effectively allow doing a const_cast without knowing the actual type being
   templated over.  I needed this because I do not in fact know that type in
   the relevant code.  I'm open to suggestions for a better name for this
   method.
2) Adds some operator& to RootedJSValue to make it look more like a JS::Value,
   and in particular so I can JS_WrapValue the thing in it.
3) Adds a Slot() method to NonNullLazyRootedObject, just like NonNull has.
4) Adds an operator& to LazyRootedObject to make it look more like JSObject* so
   I can JS_WrapObject the thing in it.
5) Implements the actual rewrapping of the arguments into the content compartment.
6) Fixes a small preexisting bug in which we didn't look at named constructors
   in getTypesFromDescriptor (this was causing my tests to not compile).
7) Changes Xrays to not enter the content compartment when calling a WebIDL
   constructor.
8) Adds some friend API to report things as not being functions.
Bug 857836 - Assertion failure: paTypeObject->getPropertyCount() == NumFixedSlots, at builtin/ParallelArray.cpp. r=bhackett, a=akeybl
Bug 863766 - Crash when destroying a JSContext with outstanding requests. r=luke, a=bajaj
Bug 857555 - Make window.content return an existing named frame with that name if there is one. r=bholley, a=akeybl