Open a new tab in an existing window.
The goal of this extension is to allow launching chrome://newtab in an
existing Chrome window via a desktop shortcut, script, slickrun command, etc.
Following a shortcut to chrome://newtab seems to always open a new window.
Navigating to the URL using JS in a static page won't work because the page
cannot access chrome:// URLs. Thus, an extension and a cooperative HTML page
are required. See newtab.html.