test($http): ignore date-toJSON test if running in IE8

IE8 does not implement Date.prototype.toISOString(), which is necessary for this feature. The
feature still works if this method is polyfilled, but these tests are not run with polyfills.

test/ng/httpSpec.js

@@ -463,6 +463,7 @@ describe('$http', function() {
       });
 
       it('should not double quote dates', function() {
+        if (msie < 9) return;
         $httpBackend.expect('GET', '/url?date=2014-07-15T17:30:00.000Z').respond('');
         $http({url: '/url', params: {date:new Date('2014-07-15T17:30:00.000Z')}, method: 'GET'});
       });