Change the default appearance of date/time input types on Android.

This CL changes it to -webkit-appearance:menulist, which is same as SELECT, from
-webkit-appearance:menulist-button, which draws bezeled border and an arrow.

BUG=343833
TEST=automated

Review URL: https://codereview.chromium.org/163613007

git-svn-id: svn://svn.chromium.org/blink/trunk@167168 bbb929c8-8fbe-4397-9dbb-9b2b20218538