Related issue:
- https://github.com/gorhill/uBlock/issues/1744
A new context menu entry, "Block element in frame...", will
be present when right-clicking on a frame element. When
this entry is clicked, uBO's element picker will be
launched from within the embedded frame and function the
same way as when launched from within the page.
No need to store mouse coordinates in background
page, thus no need to post mouse coordinates
information for every click.
Rename/group element picker arguments and popup
arguments separately.
.jshintrc's otion-set is a personal choice, merely a suggestion.
Beside that, it includes some common globals for specific browsers, so
there's no need to set the globals in every .js file.
In order to force strict coding, "use strict" directive was added into
every .js file.
