fix(mocks): $timeout.flushNext should throw an exception

we can't use Jasmine's `expect` here since this code should be library agnostic

Author: IgorMinar

src/ngMock/angular-mocks.js

@@ -131,8 +131,9 @@ angular.mock.$Browser = function() {
   self.defer.flushNext = function(expectedDelay) {
     var tick = self.deferredFns.shift();
 
-    if (angular.isDefined(expectedDelay)) {
-      expect(tick.time).toEqual(expectedDelay);
+    if (angular.isDefined(expectedDelay) && (tick.time !== expectedDelay)) {
+      throw new Error("Expected a task to be scheduled with " + expectedDelay + "ms delay, but it was " + tick.time +
+                      "ms.");
     }
 
     tick.fn();

test/ngMock/angular-mocksSpec.js

@@ -430,6 +430,16 @@ describe('ngMock', function() {
       $timeout.flushNext();
       $timeout.flushNext();
     }));
+
+
+    it("should throw an exception when flushed with flushNext and the expectedDelay doesn't match the actual delay",
+        inject(function($timeout) {
+      $timeout(function() {}, 100);
+
+      expect(function() {
+        $timeout.flushNext(4000);
+      }).toThrow("Expected a task to be scheduled with 4000ms delay, but it was 100ms.");
+    }));
   });