Revert "Revert "Blob constructor""

lib/dom/templates/html/frog/factoryprovider_Blob.darttemplate

Index: lib/dom/templates/html/frog/factoryprovider_Blob.darttemplate
diff --git a/lib/dom/templates/html/frog/factoryprovider_Blob.darttemplate b/lib/dom/templates/html/frog/factoryprovider_Blob.darttemplate
new file mode 100644
index 0000000000000000000000000000000000000000..73a1178307c81409105e8ffb844ea88091cb9533
--- /dev/null
+++ b/lib/dom/templates/html/frog/factoryprovider_Blob.darttemplate
@@ -0,0 +1,24 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class $FACTORYPROVIDER {
+  factory Blob(List blobParts = null, [String type, String endings]) {
+    // TODO: validate that blobParts is a JS Array and convert if not.
+    // TODO: any coercions on the elements of blobParts, e.g. coerce a typed
+    // array to ArrayBuffer if it is a total view.
+    if (type == null && endings == null) {
+      return _create_1(blobParts);
+    }
+    var bag = _create_bag();
+    if (type != null) _bag_set(bag, 'type', type);
+    if (endings != null) _bag_set(bag, 'endings', endings);
+    return _create_2(blobParts, bag);
+  }
+
+  static _create_1(parts) native 'return new Blob(parts);';
+  static _create_2(parts, bag) native 'return new Blob(parts, bag);';
+
+  static _create_bag() native 'return {}';
+  static _bag_set(bag, key, value) native 'bag[key] = value;';
+}