Teach SkyView code path to print hello, world

This CL makes the SkyView codepath smart enough to print "hello, world" to the
console. The code path is off by default but can be enabled by changing one
line of code.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1131673011

examples/raw/hello_world.dart

+// 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.
+
+void main() {
+    print("Hello, world");
+}