Merge pull request #368 from status200/ember-cli-2.13-compat

Monkeypatch correct `concatFiles` method

Author: rwjblue

lib/ext/patch-ember-app.js

@@ -8,7 +8,8 @@ function patchEmberApp(emberApp) {
   if (emberApp.addonPreconcatTree) { return; }
 
   // Save off original implementation of the `concatFiles` hook
-  var originalConcatFiles = emberApp.concatFiles;
+  var concatDeprecated = emberApp._concatFiles !== undefined;
+  var originalConcatFiles = concatDeprecated ? emberApp._concatFiles : emberApp.concatFiles;
 
   // Install method to invoke `preconcatTree` hook on each addon
   emberApp.addonPreconcatTree = addonPreconcatTree;
@@ -17,12 +18,18 @@ function patchEmberApp(emberApp) {
   // and, if it detects that it's a concat for the app tree, invokes our
   // preconcat hook. Afterwards, we invoke the original implementation to
   // return a tree concating the files.
-  emberApp.concatFiles = function(tree, options) {
+  var concatFiles = function(tree, options) {
     if (options.annotation === 'Concat: App') {
       tree = this.addonPreconcatTree(tree);
     }
     return originalConcatFiles.apply(this, arguments);
   };
+  if (concatDeprecated) {
+    emberApp._concatFiles = concatFiles;
+  } else {
+    emberApp.concatFiles = concatFiles;
+  }
+
 }
 
 function addonPreconcatTree(tree) {