Effects: Refactor transfer back compat to avoid bad nested return

Download builder replaces return statements while concatenating a
bundle, but fails to deal with this nested return. Since this module
is already deprecated, pulling the return to the top level makes
more sense.

Author: jzaefferer

ui/effects/effect-transfer.js

@@ -29,10 +29,12 @@
 	}
 }( function( $ ) {
 
+var effect;
 if ( $.uiBackCompat !== false ) {
-	return $.effects.define( "transfer", function( options, done ) {
+	effect = $.effects.define( "transfer", function( options, done ) {
 		$( this ).transfer( options, done );
 	} );
 }
+return effect;
 
 } ) );