perf($q): reduce closures when resolving promises

- changes Deferred.$$resolve to only wrap the internal resolve/reject when wrapping another promise

Author: jbedard

src/ng/q.js

@@ -243,18 +243,6 @@ function $$QProvider() {
  */
 function qFactory(nextTick, exceptionHandler) {
   var $qMinErr = minErr('$q', TypeError);
-  function callOnce(self, resolveFn, rejectFn) {
-    var called = false;
-    function wrap(fn) {
-      return function(value) {
-        if (called) return;
-        called = true;
-        fn.call(self, value);
-      };
-    }
-
-    return [wrap(resolveFn), wrap(rejectFn)];
-  }
 
   /**
    * @ngdoc method
@@ -361,21 +349,42 @@ function qFactory(nextTick, exceptionHandler) {
     },
 
     $$resolve: function(val) {
-      var then, fns;
+      var then;
+      try {
+        then = (isObject(val) || isFunction(val)) && isFunction(then = val.then) ? then : false;
+      } catch (e) {
+        this.$$reject(e);
+        exceptionHandler(e);
+        return;
+      }
 
-      fns = callOnce(this, this.$$resolve, this.$$reject);
+      if (then) {
+        this.promise.$$state.status = -1;
+        this.$$delayResolve(val, then);
+      } else {
+        this.promise.$$state.value = val;
+        this.promise.$$state.status = 1;
+        scheduleProcessQueue(this.promise.$$state);
+      }
+    },
+
+    $$delayResolve: function(promiseLike, then) {
+      var that = this;
+      var done = false;
+      function resolvePromise(val) {
+        if (done) return;
+        done = true;
+        that.$$resolve(val);
+      }
+      function rejectPromise(val) {
+        if (done) return;
+        done = true;
+        that.$$reject(val);
+      }
       try {
-        if ((isObject(val) || isFunction(val))) then = val && val.then;
-        if (isFunction(then)) {
-          this.promise.$$state.status = -1;
-          then.call(val, fns[0], fns[1], this.notify);
-        } else {
-          this.promise.$$state.value = val;
-          this.promise.$$state.status = 1;
-          scheduleProcessQueue(this.promise.$$state);
-        }
+        then.call(promiseLike, resolvePromise, rejectPromise, this.notify);
       } catch (e) {
-        fns[1](e);
+        rejectPromise(e);
         exceptionHandler(e);
       }
     },