Consistent 'this' between befores/it/afters

Change the 'this' user functions are called with to be an empty object
instead of the QueueRunner so that if the user puts properties on it,
        they won't conflict.

Also, changes async specs to be called with a proper 'this', as pointed
out by @Eric-Wright in #419 and #420.

[finishes #56030080]

src/core/QueueRunner.js

@@ -6,6 +6,7 @@ getJasmineRequireObj().QueueRunner = function() {
     this.clearStack = attrs.clearStack || function(fn) {fn();};
     this.onException = attrs.onException || function() {};
     this.catchException = attrs.catchException || function() { return true; };
+    this.userContext = {};
   }
 
   QueueRunner.prototype.execute = function() {
@@ -34,7 +35,7 @@ getJasmineRequireObj().QueueRunner = function() {
 
     function attemptSync(fn) {
       try {
-        fn.call(self);
+        fn.call(self.userContext);
       } catch (e) {
         handleException(e);
       }
@@ -44,7 +45,7 @@ getJasmineRequireObj().QueueRunner = function() {
       var next = function () { self.run(fns, iterativeIndex + 1); };
 
       try {
-        fn.call(self, next);
+        fn.call(self.userContext, next);
       } catch (e) {
         handleException(e);
         next();