As of C1 4.3, i've replaced the custom implementation of the BrowserHelper class with the native ones shipped in WebPages 3. This also means the usage of the DisplayModeProvider class, which support adding custom modes and resolving.
https://bitbucket.org/burningice/composite-c1-community-edition/commits/93f3b782c0a0a9996ecaa32b6eef519d52840e3b
https://bitbucket.org/burningice/composite-c1-community-edition/commits/93f3b782c0a0a9996ecaa32b6eef519d52840e3b