Move third_party/clang to cloud storage

DEPS

 # 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.
 
 vars = {
   # The dart_root is the root of our sdk checkout. This is normally
   # simply sdk, but if using special gclient specs it can be different.
   "dart_root": "sdk",
 
-  # The svn location to pull out dependencies from
-  "third_party": "http://dart.googlecode.com/svn/third_party",
-
   # We use mirrors of all github repos to guarantee reproducibility and
   # consistency between what users see and what the bots see.
   # We need the mirrors to not have 100+ bots pulling github constantly.
   # We mirror our github repos on chromium git servers.
   # DO NOT use this var if you don't see a mirror here:
   #   https://chromium.googlesource.com/
   # named like:
   #   external/github.com/dart-lang/NAME
   # It is ok to add a dependency directly on dart-lang (dart-lang only)
   # github repo until the mirror has been created, but please do file a bug
   # against infra to make that happen.
   "github_mirror":
       "https://chromium.googlesource.com/external/github.com/dart-lang/%s.git",
 
   "gyp_rev": "@6ee91ad8659871916f9aa840d42e1513befdf638",
   "co19_rev": "@3ed795ea02e022ef19c77cf1b6095b7c8f5584d0",
   "chromium_git": "https://chromium.googlesource.com",
 
   # Revisions of /third_party/* dependencies.
   "args_tag": "@0.13.0",
   "async_tag": "@1.4.0",
   "barback_tag" : "@0.15.2+7",
   "boringssl_rev" : "@daeafc22c66ad48f6b32fc8d3362eb9ba31b774e",
   "charcode_tag": "@1.1.0",
   "chrome_rev" : "@19997",
-  "clang_rev" : "@28450",
   "cli_util_tag" : "@0.0.1+2",
   "collection_rev": "@f6135e6350c63eb3f4dd12953b8d4363faff16fc",
   "convert_tag": "@1.0.0",
   "crypto_rev" : "@2df57a1e26dd88e8d0614207d4b062c73209917d",
   "csslib_tag" : "@0.12.0",
   "dart2js_info_rev" : "@0a221eaf16aec3879c45719de656680ccb80d8a1",
   "dartdoc_tag" : "@v0.8.4",
   "dart_services_rev" : "@7aea2574e6f3924bf409a80afb8ad52aa2be4f97",
   "dart_style_tag": "@0.2.2",
   "dev_compiler_rev": "@0.1.9",
@@ skipping 234 matching lines @@
   "android": {
     Var("dart_root") + "/third_party/android_tools":
       Var("chromium_git") + "/android_tools.git" +
       "@aaeda3d69df4b4352e3cac7c16bea7f16bd1ec12",
   },
   "win": {
     Var("dart_root") + "/third_party/cygwin":
       Var("chromium_git") + "/chromium/deps/cygwin.git" +
       "@c89e446b273697fadf3a10ff1007a97c0b7de6df",
   },
-  "unix": {
-    Var("dart_root") + "/third_party/clang":
-      Var("third_party") + "/clang" + Var("clang_rev"),
-  },
 }
 
 # TODO(iposva): Move the necessary tools so that hooks can be run
 # without the runtime being available.
 hooks = [
   {
     "pattern": ".",
     "action": ["python", Var("dart_root") + "/tools/gyp_dart.py"],
   },
   {
@@ skipping 106 matching lines @@
       "download_from_google_storage",
       "--no_auth",
       "--no_resume",
       "--bucket",
       "dart-dependencies",
       "--extract",
       "-s",
       Var('dart_root') + "/third_party/gsutil.tar.gz.sha1",
     ],
   },
+  {
+    "name": "clang",
+    "pattern": ".",
+    "action": [
+      "download_from_google_storage",
+      "--no_auth",
+      "--no_resume",
+      "--bucket",
+      "dart-dependencies",
+      "--platform=linux*",
+      "--extract",
+      "-s",
+      Var('dart_root') + "/third_party/clang.tar.gz.sha1",
+    ],
+  },
 ]