Move serial out of experimental.

chrome/common/extensions/api/_permission_features.json

 // Copyright (c) 2012 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.
 
 {
   "activeTab": {
     "channel": "dev",
     "extension_types": ["extension", "packaged_app"],
     "min_manifest_version": 2
   },
@@ skipping 218 matching lines @@
     "extension_types": ["extension", "packaged_app"]
   },
   // Note: runtime is not actually a permission, but some systems check these
   // values to verify restrictions.
   "runtime": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "min_manifest_version": 2
   },
   "serial": {
-    "channel": "stable",
+    "channel": "dev",
     "extension_types": ["platform_app"]
   },
   "socket": {
     "channel": "dev",
     "extension_types": ["platform_app"]
   },
   "storage": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "min_manifest_version": 2
@@ skipping 26 matching lines @@
   "ttsEngine": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "unlimitedStorage": {
     "channel": "stable",
     "extension_types": [
       "extension", "packaged_app", "hosted_app", "platform_app"
     ]
   },
   "usb": {

[asargent_no_longer_on_chrome, 2012/08/03 23:41:07]

should we remove this entry for usb?

     "channel": "stable",
     "extension_types": ["platform_app"]
   },
   "videoCapture": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   },
   "wallpaperPrivate": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"],
@@ skipping 24 matching lines @@
   },
   "webRequest": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   }
 }