chore(lint): require semicolons

Relying on ASI (automatic semicolon insertion)
is allowed in TypeScript because JavaScript allows
it. However, when we run clang-format it doesn’t
understand that these statements are terminated
with a newline and changes the indentation, in bad
cases even breaking the code.

Fixes #817

modules/angular2/src/forms/validators.ts

@@ -26,7 +26,7 @@ export class Validators {
         return isPresent(errors) ? StringMapWrapper.merge(res, errors) : res;
       }, {});
       return StringMapWrapper.isEmpty(res) ? null : res;
-    }
+    };
   }
 
   static group(c: modelModule.ControlGroup): StringMap<string, boolean> {