hide selection handle when start typing

[Robin Heroldich]

This is a similar bug report as this: https://bugs.launchpad.net/ubuntu/+source/webbrowser-app/+bug/1590776

Just this is about the standard UI toolkit component for text input, not for the oxide ones. I think it would be good if the system manages this the same everywhere. So please implement the same feature for this too. Thanks.

Description of the Oxide bug report for easier understand:

we are showing the selection handle (in addition to the cursor) whenever entering a text field that already has text in it. For example, if you are replying to a Gmail message, you have an annoying blue selection handle blinking where you are trying to type and you can't turn it off. Or on a form, focusing on a field to append text will also show the selection handle. Or a multi line text area, adding a new line and typing at the beginning.

Tested Chrome on Android and it behaves differently, and think we should do similar:
 1. Show the selection handle initially, but have it disappear when you press any key (space, character, etc.)
 2. Tapping anywhere in the field will cause handle to be shown again
 3. Also, can we put the selection handle on the bottom of the cursor instead of the top? This is the behavior on Chrome for Android and the rest of our non-html platform in Ubuntu touch.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.