Support self-referential package: imports with Pub.

utils/pub/sdk_source.dart

Index: utils/pub/sdk_source.dart
diff --git a/utils/pub/sdk_source.dart b/utils/pub/sdk_source.dart
index 75dd62c369a408154ef70a5b66724c835a3102cc..5984555fe3bb300bfcb0fd6d313597e4fc2f0218 100644
--- a/utils/pub/sdk_source.dart
+++ b/utils/pub/sdk_source.dart
@@ -39,7 +39,7 @@ class SdkSource extends Source {
   Future<Pubspec> describe(PackageId id) {
     return readTextFile(join(rootDir, "revision")).transform((revision) {
       var version = new Version.parse("0.0.0-r.${revision.trim()}");
-      return new Pubspec(version, <PackageRef>[]);
+      return new Pubspec(id.name, version, <PackageRef>[]);
     });
   }