Fix 'error: cannot find symbol' error

Summary: This slipped through in another diff. :/

Test Plan:
```
$ mvn clean install
...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] selendroid ......................................... SUCCESS [  0.103 s]
[INFO] android-driver-app ................................. SUCCESS [  1.962 s]
[INFO] selendroid-server-common ........................... SUCCESS [  0.823 s]
[INFO] selendroid-server .................................. SUCCESS [ 14.917 s]
[INFO] selendroid-grid-plugin ............................. SUCCESS [  0.569 s]
[INFO] selendroid-common .................................. SUCCESS [  0.826 s]
[INFO] selendroid-standalone .............................. SUCCESS [ 15.737 s]
[INFO] selendroid-client .................................. SUCCESS [  0.532 s]
[INFO] selendroid-test-app ................................ SUCCESS [  4.301 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
```

Reviewers: mkonicek

Reviewed By: mkonicek

Differential Revision: https://reviews.facebook.net/D29241