Change rake test:js to run headless.

To run tests in browser, use rake test:js_in_browser.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Implement Edit Track synchronization between tabs/windows.

The use of WebStorage API requires browser IE 8+ and equivalent.

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>