Replacing the top frame with a data-uri is forbidden since chromium-based-webview version 60.
With this commit we swap the body with an iframe when needed. Old webviews work as usual also with this approach.
No special treatment is needed for local storage as its usage is forbidden in data-uri iframes.
Fixes#758
- localstorage is now cleared at every launch: this prevents some clay configuration pages to send back to the watch a number of keys that were set by other configuration pages
- only execute JS on document ready: this prevents some race conditions
- added dummy getTimelineToken function to Pebble JS object
- corrected (hopefully!) a few logic errors in the JS code (this referenced where it wasn't)
- refactored the steps visualization in JS
- lifecycle changes to the java activity: now the configuration page gets closed as soon as the settings have been sent, and there is only one instance of it
