Update WebViewTest#testSetPictureListener.

From JBMR2, clients should now expect a null
picture to be returned in the WebView.PictureListener.onNewPicture
callback, so update the tests to reflect this.

Bug: 8209022
Change-Id: I86a672616ed728e33eb0197af9130b48ed59efb0
diff --git a/tests/tests/webkit/src/android/webkit/cts/WebViewTest.java b/tests/tests/webkit/src/android/webkit/cts/WebViewTest.java
index eff9640..05b2d6e 100755
--- a/tests/tests/webkit/src/android/webkit/cts/WebViewTest.java
+++ b/tests/tests/webkit/src/android/webkit/cts/WebViewTest.java
@@ -606,7 +606,7 @@
             }
         }.run();
         assertEquals(mWebView, listener.webView);
-        assertNotNull(listener.picture);
+        assertNull(listener.picture);
 
         final int oldCallCount = listener.callCount;
         final String newUrl = mWebServer.getAssetUrl(TestHtmlConstants.SMALL_IMG_URL);