With the recent popularity of Chromebooks, I have been playing around with CloudReady's free ChromiumOS on an old laptop, but was disappointed to see that you can't run Plover on them, without installing a second OS.
But it turns out the Chrome Extension framework contains pretty-much everything you need to write a Chrome extension with similar functionality.
I've had some time-off recently, and was intrigued, so I began to see what I could create. I have attached the preliminary version so far. (Unfortunately it only works on ChromeBooks).
To install, open chrome://extensions, and drag the .crx file on to the page. Then in order to enable it, you need to open your settings page, search for "Keyboard", select "Language and Input settings", and check "Steno Keyboard" under "Input Method". Once it's enabled you can select your input method by clicking in the Status Area (bottom right).