TART - Tab Animation Regression Test

#### TART - Tab Animation Regression Tests

Visit talos/TART for detailed info.

- If you just opened the browser - give Firefox few seconds to settle down before testing.
- (requires restart to take effect). TART runs best (and in talos) with vsync disabled - to measure maximum throughput (ASAP mode). This means the preferences layout.frame_rate = 0 and docshell.event_starvation_delay_hint = 1
- In talos, TART runs with a single tab. If you wish to test a specific animation with several tabs open, you can do so as well by manually opening few tabs before starting the test.

Utilities: blank with icon about:config (already filtered with relevant prefs)
Configure TART (CTRL-F5 to reset to talos defaults)
Repeat: times
Delay before starting a measured animation: ms
Pause the profiler during animations which are not measured.
Accurate first recorded frame (tickle the Back button before measurements)
Testing in progress ...