Import org.junit.Assert instead of junit.framework.Assert.

This fixed the warning:
app/webrtc/java/testcommon/src/org/webrtc/PeerConnectionTest.java:46: warning: [deprecation] Assert in junit.framework has been deprecated
import static junit.framework.Assert.*;

R=glaznev@webrtc.org, pthatcher@webrtc.org
BUG=none

Review URL: https://webrtc-codereview.appspot.com/50209004

Cr-Commit-Position: refs/heads/master@{#9356}
1 file changed