Do not retry failed attempts to retry scrolls.

Bug:3174399

If the page requests to scroll beyond the edge of the
screen, we send a message to try again on a draw, in case
our picture is out of date and the page should be larger.
However, sometimes we get stuck in a loop of retrying the
same scroll position over and over again.  End this loop.

Change-Id: I53fcd4c2fa70c7ef63d4537d8b24eabb6b924b0b

core/java/android/webkit/WebView.java

@@ -6443,7 +6443,8 @@ public class WebView extends AbsoluteLayout
                         mUserScroll = false;
                         break;
                     }
-                    // fall through
+                    setContentScrollTo(msg.arg1, msg.arg2);
+                    break;
                 case SCROLL_TO_MSG_ID:
                     if (setContentScrollTo(msg.arg1, msg.arg2)) {
                         // if we can't scroll to the exact position due to pin,