Shadow DOM: Move handleDOMActivateEvent back from InputTypeView to InputType.

This affects input[type=color], input[type=file], input[type=image],
input[type=reset], and input[type=submit]. Without this change, web authors have
no ways to open a file chooser dialog.

We exclude BaseChooserOnlyDateAndTimeInputType::handleDOMActivateEvent,
Date/time input types on Android, because of consistency with non-Android ports,
which don't respond to DOMActivate.

Also, this CL makes it possible to test if a file chooser is opened.

BUG=274205
TEST=automated.

Review URL: https://chromiumcodereview.appspot.com/23484032

git-svn-id: svn://svn.chromium.org/blink/trunk@157648 bbb929c8-8fbe-4397-9dbb-9b2b20218538