Make DevTools panel translatable
Unlike all of our other UIs, the Adblock Plus DevTools panel is only available in English. Existing texts were hardcoded and are therefore not even available for translations yet.
What to change
Move all strings in the DevTools panel (specified here eyeo/specs/spec!171 (merged)) to locale/en_US/devtools-panel.json.
Hints for translators
Added devtools-panel.json file.