Support .data( 'sortkey' ) to enable list sorting by its sortkey

+ Replace minified version with standard JS
+ Add .data( 'sortkey' ) check to set firstChar

## Depends on
+ Change If44e2754e69

Change-Id: I0244c01d2da4745c152248356699460e4ef688cb
Merge "Support .data( 'sortkey' ) to enable list sorting by its sortkey"