Create an apptesting framework for dart.

mojo/dart/apptest/BUILD.gn

Index: mojo/dart/apptest/BUILD.gn
diff --git a/examples/dart/hello_world/hello/BUILD.gn b/mojo/dart/apptest/BUILD.gn
similarity index 66%
copy from examples/dart/hello_world/hello/BUILD.gn
copy to mojo/dart/apptest/BUILD.gn
index 7c77e84659dd2135b37fffe738722962f2e60ab4..0c8365e81ca0b6b74311d358c1e6b905f94e6244 100644
--- a/examples/dart/hello_world/hello/BUILD.gn
+++ b/mojo/dart/apptest/BUILD.gn
@@ -4,12 +4,11 @@
 
 import("//mojo/public/dart/rules.gni")
 
-dart_packaged_application("hello") {
+dart_package("apptest") {

[tonyg, 2015/03/02 22:43:31]

Are we planning to make this public?

[Elliot Glaysher, 2015/03/02 23:33:37]

Yes. I assumed that this dartzip would be a product that could be used in other
repos. Is there something further that I have to do around this?

[tonyg, 2015/03/03 00:07:55]

I think Hans and Scott were talking about a solution for this earlier today.

   sources = [
-    "main.dart",
+    "apptest/apptest.dart",
   ]
   deps = [
-    "//mojo/public/interfaces/application",
+    "//third_party/dart-packages/unittest",
   ]
-  strict = is_debug
 }