fix(closure): Fix closure error suppression comment. (#552)

Fix the formatting of the comment so that it's properly picked up by closure.

Author: vikerman

Diff for: lib/common/utils.ts

@@ -5,9 +5,8 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-
 /**
- * Suppress closure compiler errors about unknown 'process' variable
+ * Suppress closure compiler errors about unknown 'Zone' variable
  * @fileoverview
  * @suppress {undefinedVars}
  */