Fix Directory.create(recursive: true) for non-existing paths.

sdk/lib/io/directory_impl.dart

Index: sdk/lib/io/directory_impl.dart
diff --git a/sdk/lib/io/directory_impl.dart b/sdk/lib/io/directory_impl.dart
index d96151f329d0144cf7a9923eb543d4a712ee68dc..d3c6a1406ecb24b64cf4f0990d258d8a6a676c13 100644
--- a/sdk/lib/io/directory_impl.dart
+++ b/sdk/lib/io/directory_impl.dart
@@ -52,22 +52,25 @@ class _Directory implements Directory {
     return (result == 1);
   }
 
+  // Compute the index of the first directory in the list that exists. If
+  // none of the directories exist dirsToCreate.length is returned.
   Future<int> _computeExistingIndex(List dirsToCreate) {
     var future;
+    var notFound = dirsToCreate.length;
     for (var i = 0; i < dirsToCreate.length; i++) {
       if (future == null) {
-        future = dirsToCreate[i].exists().transform((e) => e ? i : -1);
+        future = dirsToCreate[i].exists().transform((e) => e ? i : notFound);
       } else {
         future = future.chain((index) {
-          if (index != -1) {
+          if (index != notFound) {
             return new Future.immediate(index);
           }
-          return dirsToCreate[i].exists().transform((e) => e ? i : -1);
+          return dirsToCreate[i].exists().transform((e) => e ? i : notFound);
         });
       }
     }
     if (future == null) {
-      return new Future.immediate(-1);
+      return new Future.immediate(notFound);
     } else {
       return future;
     }
@@ -85,6 +88,8 @@ class _Directory implements Directory {
       path = path.directoryPath;
     }
     return _computeExistingIndex(dirsToCreate).chain((index) {
+      // If none of the directories already exist we need to create them all.
+      if (index == -1) index = dirsToCreate.length;

[Søren Gjesse, 2013/01/03 15:11:13]

I can't figure out how the _computeExistingIndex can complete with -1.

[Mads Ager (google), 2013/01/03 16:04:16]

D'oh! That was what it used to do, so this was my first 'fix' which I didn't
like. I forgot to remove it again. :-)

       var future;
       for (var i = index - 1; i >= 0 ; i--) {
         if (future == null) {