Rated 5 out of 5 stars

Perfect, thanks!.
I suggest to support icons for the context menu. That would be something like
menuitem[label="View This Page in Chrome"] {
list-style-image: url("chrome://chromeview/skin/toolbar-16-enabled.png") !important;
}
or even better (for multi-language-support) same thing with an id instead of going with the label.

This review is for a previous version of the add-on (0.2.0).