Bug 887334 - Add a JSCompartment* to AutoCompartment and use it in JS_NewGlobalObject. r=luke

This gets rid of the wonky setCompartment usage in that function.

js/src/jsapi.cpp

@@ -3318,10 +3318,12 @@ JS_NewGlobalObject(JSContext *cx, JSClass *clasp, JSPrincipals *principals,
 
     AutoHoldZone hold(compartment->zone());
 
-    JSCompartment *saved = cx->compartment();
-    cx->setCompartment(compartment);
-    Rooted<GlobalObject *> global(cx, GlobalObject::create(cx, Valueify(clasp)));
-    cx->setCompartment(saved);
+    Rooted<GlobalObject *> global(cx);
+    {
+        AutoCompartment ac(cx, compartment);
+        global = GlobalObject::create(cx, Valueify(clasp));
+    }
+
     if (!global)
         return NULL;
 

js/src/jscompartment.h

@@ -460,6 +460,7 @@ class AutoCompartment
 
   public:
     inline AutoCompartment(JSContext *cx, JSObject *target);
+    inline AutoCompartment(JSContext *cx, JSCompartment *target);
     inline ~AutoCompartment();
 
     JSContext *context() const { return cx_; }

js/src/jscompartmentinlines.h

@@ -33,6 +33,13 @@ js::AutoCompartment::AutoCompartment(JSContext *cx, JSObject *target)
     cx_->enterCompartment(target->compartment());
 }
 
+js::AutoCompartment::AutoCompartment(JSContext *cx, JSCompartment *target)
+  : cx_(cx),
+    origin_(cx->compartment())
+{
+    cx_->enterCompartment(target);
+}
+
 js::AutoCompartment::~AutoCompartment()
 {
     cx_->leaveCompartment(origin_);