Fix saving error of video editor in non-english translation

Currently the code in ```tabs-aggregator.coffee``` uses the display name of a tab as the key to index the current tab. When a non-english translation is applied, the javascript code will get localized names instead of the original english names, which causes the following ```getValue``` function fails as it cannot reference the correct tab.
Use the 'data' attribute to store the original tab name.
Merge pull request #4217 from louyihua/master

Fix saving error of video editor with non-english translations