Fixing IndexedDB's deleteDatabase to have the correct future result.

tools/dom/templates/html/impl/impl_IDBFactory.darttemplate

Index: tools/dom/templates/html/impl/impl_IDBFactory.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_IDBFactory.darttemplate b/tools/dom/templates/html/impl/impl_IDBFactory.darttemplate
index 842b6f42895cd30d08cebef312e906f69903ebf1..6b2501b7bd5d6083f4184c6dcd31d6e19d0159ee 100644
--- a/tools/dom/templates/html/impl/impl_IDBFactory.darttemplate
+++ b/tools/dom/templates/html/impl/impl_IDBFactory.darttemplate
@@ -56,7 +56,14 @@ $endif
       if (onBlocked != null) {
         request.onBlocked.listen(onBlocked);
       }
-      return _completeRequest(request);
+      var completer = new Completer.sync();
+      request.onSuccess.listen((e) {
+        completer.complete(this);
+      });
+      request.onError.listen((e) {
+        completer.completeError(e);
+      });
+      return completer.future;
     } catch (e, stacktrace) {
       return new Future.error(e, stacktrace);
     }