Bug 914432 - Add support for multiple prefs to enable/disable values in the same property keyword table.  r=dbaron
Bug 929991 - Style system implementation of 'text-align: true X'.  r=heycam
Bug 929991 - Put 'text-align: true X' support behind a preference (disabled by default).  r=heycam
Bug 929991 - Layout implementation of 'text-align: true X'.  r=roc
Bug 929991 - Tests for text-align: true X;