Correction: Add option/make default that the context menu item for "invert image" only shows up in the "image" context

Firefox has several specific contexts in which different right-click menus are displayed. I (and I think most other users) would vastly prefer the menu item for "invert image" to only show up in the "image" context, as this would save confusion and many accidental clicks.

[vycb]

The add-on show up in the "any" context to invert any part of a page for example: select parent element to invert group of an images; same to invert pdf on github..../google docs/video element/body of a page.