refactor($compile): $$addScopeInfo always expects jq wrapper

`$$addScopeInfo` used to accept either DOM Node or jqLite/jQuery
wrapper. This commit simplifies the method to always require
jqLite/jQuery wrapper and thus remove the `element.data` condition which
was wrong. If `element` was a raw comment element, the `data` property
was a string (the value of the comment) and an exception was thrown.