Remove an extraneous RequireJS optimizer invocation

Credit @jnu.

Author: carsomyr

lib/requirejs/rails/rjs_driver.js.erb

@@ -35,11 +35,10 @@ var errback = function(error) {
 // Do a series of builds of individual files, using the args suggested by:
 // http://requirejs.org/docs/optimization.html#onejs
 //
-// r.js will eventually need a nested call idiom to handle async 
+// r.js will eventually need a nested call idiom to handle async
 // builds.  Anticipating that need.
 var async_runner = module_specs.reduceRight(function(prev, curr) {
   return function (buildReportText) {
-    requirejs.optimize(mix(curr), prev);
     requirejs.optimize(mix(curr), prev, errback);
   };
 }, function(buildReportText) {} );