[ChromeDriver] Make testActionsMultiTouchPoint robust

Add a little delay between creating <div> and sending touch events,
to avoid flakiness.

Bug: 1011225, 1030260
Change-Id: I2075ff32ef8324194d1d8e2a6d6b68e644290f9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948492
Auto-Submit: John Chen <johnchen@chromium.org>
Reviewed-by: Lan Wei <lanwei@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721075}

chrome/test/chromedriver/test/run_py_tests.py

@@ -962,6 +962,7 @@ class ChromeDriverTest(ChromeDriverBaseTestWithWebServer):
               {type: event.type});
         });
         ''')
+    time.sleep(0.1)
 
     actions = ({"actions": [{
       "type":"pointer",