Bug 1111159.  Inline the IsArrayIterator and IsStringIterator intrinsics in Ion code to speed up for-of loops.  r=jandem,waldo
Bug 924059.  Give ArrayIterator and its prototype different JSClasses so we can't confuse them for each other.  r=waldo
Bug 1111166.  Don't emit a movq from a register to itself when unboxing things on x86-64.  r=sunfish
Bug 1111162.  When inlining IsObject(), if our type info says we have an object, just output a constant true instead of doing a dynamic check.  r=jandem