Adding GYP V2 targets for all Polymer code (with a script!).

third_party/polymer/v1_0/components-chromium/iron-pages/compiled_resources2.gyp

+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+{
+  'targets': [
+    {
+      'target_name': 'iron-pages-extracted',
+      'dependencies': [
+        '../iron-resizable-behavior/compiled_resources2.gyp:iron-resizable-behavior-extracted',
+        '../iron-selector/compiled_resources2.gyp:iron-selectable-extracted'
+      ],
+      'includes': [
+        '../../../../closure_compiler/compile_js2.gypi'
+      ]
+    }
+  ]
+}