Revert "Fix some tiny things"

This reverts commit 05c207c437fc4a4ab475c8f761b3676cc510de3e.
Merge branch 'master' of https://github.com/kkamperschroer/Google-Music-Applet
Don't inject contentscript into all frames. Breaks things. Need to figure out what to do for spotify...
Fix Google Music forward and back buttons.
Fixed spotify