TB9: Address bar and hotkey broken

1. Extract a fresh TB9 (I tested it with 9.0a7 and the 2019-10-08 nightly on Fedora Linux 30).

2. Before the first start, set about:blank as the homepage: {{{ export TOR_DEFAULT_HOMEPAGE=about:blank

   alternatively:

   echo 'user_pref("browser.startup.homepage", "about:blank");' >>Browser/TorBrowser/Data/Browser/profile.default/prefs.js }}}

3. Run ./start-tor-browser.desktop, connect to Tor, and wait until the main browser window opens.

After typing an URL into the address bar, it cannot be confirmed with Enter. (And autocomplete doesn't work either, e.g. "blog" is not completed to "blog.torproject.org/".) This seems to only affect the first start of a fresh TB9 installation.

If Ctrl+Shift+u (the hotkey for New Identity) is pressed while the address bar has focus, an underlined u is typed in. This problem remains even after a restart.

In contrast to #27427 (moved), the bug appears unrelated to NoScript - deleting the NoScript .xpi makes no difference. Workaround: data:, instead of about:blank as the homepage URL.

Trac:
Username: rustybird