Remove sky:init

Now that we don't have a magicaly mojom package, we don't need sky:init.

engine/src/flutter/sky/packages/workbench/BUILD.gn

@@ -1,16 +0,0 @@
-# Copyright 2015 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.
-
-action("init") {
-  stamp = "$target_gen_dir/sky_init.stamp"
-
-  script = "//sky/build/sky_init.py"
-  sources = [ "//sky/packages/sky/pubspec.yaml" ]
-  outputs = [ stamp ]
-
-  args = [
-    "--touch",
-    rebase_path(stamp, root_build_dir),
-  ]
-}

engine/src/flutter/sky/tools/skypy/skyserver.py

@@ -36,7 +36,6 @@ class SkyServer(object):
 
         env = os.environ.copy()
         env["PUB_CACHE"] = PUB_CACHE
-        subprocess.check_call([PUB, 'run', 'sky:init'], cwd=WORKBENCH_ROOT, env=env)
         args = [PUB, 'run', 'sky_tools:sky_server', str(self.port)]
         self.server = subprocess.Popen(args, cwd=WORKBENCH_ROOT, env=env)
         return self.server.pid