Fix some SpiderMonkey lint

SpiderMonkey complains about functions not always returning a value. In
most cases that is a conscious code style choice, so it is not fixed
here.

In one case (MockDate) the interpreter thought you could have fallen off
the end of a "switch" statement, although the number of arguments
prevented that. This was fixed by changing the last case to "default".

In another case (QueueRunner) the function really did return a value
sometimes and nothing other times, although as far as I could see, it
could only ever return "undefined". The function now explicitly only
returns no value.

See #751

src/core/MockDate.js

@@ -54,7 +54,7 @@ getJasmineRequireObj().MockDate = function() {
         case 6:
           return new GlobalDate(arguments[0], arguments[1], arguments[2], arguments[3],
                                 arguments[4], arguments[5]);
-        case 7:
+        default:
           return new GlobalDate(arguments[0], arguments[1], arguments[2], arguments[3],
                                 arguments[4], arguments[5], arguments[6]);
       }

src/core/QueueRunner.js

@@ -34,7 +34,8 @@ getJasmineRequireObj().QueueRunner = function(j$) {
     for(iterativeIndex = recursiveIndex; iterativeIndex < length; iterativeIndex++) {
       var queueableFn = queueableFns[iterativeIndex];
       if (queueableFn.fn.length > 0) {
-        return attemptAsync(queueableFn);
+        attemptAsync(queueableFn);
+        return;
       } else {
         attemptSync(queueableFn);
       }