[fix bug 1085703] Implement Developer browser firstrun page
Build out layout/style for Dev browser firstrun
Bug 1085703
Defer loading iframe content until user triggers the modal
Add UITour JS logic for dev firstrun
Add doorhanger icons and update UITour logic
Update firstrun view logic for dev browser
Update /tour view logic for dev fristrun
Update highlight targets for dev build
Do not re-show the final tour step
Standardize icon naming convention
Add GA tracking and links for Dev browser firstrun
Bug 1088285 & Bug 1071922
Show dev-firstrun template for whatsnew 35.0a2
Fix naming of template tests
Add valence screenshot to firstrun page
Bug 1085703
Add links to videos for dev firstrun page
Bug 1085703
Add theme revert message to dev firstrun
Bug 1085703 and Bug 1092244
Responsive layout fixes for dev firstrun
Bug 1085703
Add GA tracking for dev firstrun tour
Remove whatsnew url for dev browser as not needed
Move theme-revert message and add GA tracking
Bug 1085703