Key binding should work even when focus is in URL bar or text entry widget

[dandavison]

The native Ctrl+T can be used to open a new tab, even when focus is in the URL bar or a text entry widget, with an input cursor.

However, with this extension, in that situation, the key event is interpreted as text input (so e.g. I get ç on MacOS, instead of a new tab).

This may be currently impossible, but I think it's worth opening the issue since really, if an extension is going to provide the new-tab functionality, we do want this behaviour. For example, a natural workflow is Ctrl-l Ctrl-c Ctrl-t Ctrl-v to open a new tab with a URL derived from the current one by manual editing.

[fxedel]

Can't reproduce this in Linux (Ubuntu 17.10).