chore(build): add Firefox to CI

modules/angular2/test/forms/integration_spec.ts

@@ -14,7 +14,8 @@ import {
   it,
   inject,
   iit,
-  xit
+  xit,
+  isFirefox
 } from 'angular2/test_lib';
 
 import {DOM} from 'angular2/src/dom/dom_adapter';
@@ -737,6 +738,13 @@ export function main() {
                   rootTC.componentInstance.form = form;
                   rootTC.detectChanges();
 
+                  // In Firefox, effective text selection in the real DOM requires an actual focus
+                  // of the field. This is not an issue in a new HTML document.
+                  if (isFirefox()) {
+                    var fakeDoc = DOM.createHtmlDocument();
+                    DOM.appendChild(fakeDoc.body, rootTC.nativeElement);
+                  }
+
                   var input = rootTC.query(By.css("input")).nativeElement;
                   input.value = "aa";
                   input.selectionStart = 1;