Fix erroneous VR test behavior change

One of the tests that uses the DON flow was erroneously changed during
the XR test refactor to use enterSessionWithUserGestureOrFail instead
of enterSessionWithUserGestureAndWait, causing it to fail 100% of the
time.

TBR=mthiessse@chromium.org

Change-Id: I6d05fa052f2d13998b2c25f3d0f80b6d5b7681ca
Reviewed-on: https://chromium-review.googlesource.com/1142510Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576234}

chrome/android/javatests/src/org/chromium/chrome/browser/vr/WebXrVrTransitionTest.java

@@ -246,7 +246,7 @@ public class WebXrVrTransitionTest {
     private void presentationPromiseUnresolvedDuringDonImpl(
             String url, WebXrVrTestFramework framework) throws InterruptedException {
         framework.loadUrlAndAwaitInitialization(url, PAGE_LOAD_TIMEOUT_S);
-        framework.enterSessionWithUserGestureOrFail();
+        framework.enterSessionWithUserGestureAndWait();
         framework.endTest();
     }