Bug 1059224 - [v2.1] Update browser launch method to use manifest url in...

...stead of app name
@zacc I removed that block.
@davehunt The javascript method will not work if you pass None as an argument because it is converted to string. To work around this issue I updated the javascript [method][link].

[link]:https://github.com/mozilla-b2g/gaia/pull/23369/files#diff-507d02ce236ea5ec35a3aa5b3e5b051dR306