Fix WebViewClient form submission CTS failure

Since we picked up webkit r65340, we cannot trigger a page navigation
in the onload handler and expect it to create a history entry. We must
do the navigation asynchronously.

Requires a change in external/webkit, see

Bug: 3241908

Change-Id: I8cefff3aeb0e05c63b4b7900777096abe2937841
1 file changed