Update test for Chrome 51

Change-Id: Idea068b22acc0955a272db3da5f555a7ee0d902f

uitest/src/test/java/com/vaadin/tests/VerifyBrowserVersionTest.java

@@ -40,7 +40,7 @@ public class VerifyBrowserVersionTest extends MultiBrowserTest {
             // Chrome version does not necessarily match the desired version
             // because of auto updates...
             browserIdentifier = getExpectedUserAgentString(getDesiredCapabilities())
-                    + "50";
+                    + "51";
         } else {
             browserIdentifier = getExpectedUserAgentString(desiredCapabilities)
                     + desiredCapabilities.getVersion();