Dynamically load packages for dartdevc tests in test.dart.

tools/testing/dart/utils.dart

Index: tools/testing/dart/utils.dart
diff --git a/tools/testing/dart/utils.dart b/tools/testing/dart/utils.dart
index ee14293d754899916bd5956ccbd4361ca448744c..f0a59a95c7c58966efbd6b7494e87948d34d53fc 100644
--- a/tools/testing/dart/utils.dart
+++ b/tools/testing/dart/utils.dart
@@ -19,6 +19,19 @@ String MAX_STDIO_DELAY_PASSED_MESSAGE =
  ($MAX_STDIO_DELAY passed). Please note that this could be an indicator
  that there is a hanging process which we were unable to kill.""";
 
+/// The names of the packages that are available for use in tests.
+const testPackages = const [
+  "async_helper",
+  "collection",
+  "expect",
+  "js",
+  "matcher",
+  "meta",
+  "path",
+  "stack_trace",
+  "unittest"
+];
+
 class DebugLogger {
   static IOSink _sink;