Initial support to test.dart for running precompiler tests on android devices

tools/test.dart

Index: tools/test.dart
diff --git a/tools/test.dart b/tools/test.dart
index bbfdf258cfedc62378168386c7bea12fdf7aa3cd..48a7d082e0b46a1179d56afd196131ee902807ea 100755
--- a/tools/test.dart
+++ b/tools/test.dart
@@ -57,11 +57,11 @@ Future _deleteTemporaryDartDirectories() {
 void main(List<String> arguments) {
   // This script is in [dart]/tools.
   TestUtils.setDartDirUri(Platform.script.resolve('..'));
-  _deleteTemporaryDartDirectories().then((_) {
+  _deleteTemporaryDartDirectories().then((_) async {
     var optionsParser = new TestOptionsParser();
     var configurations = optionsParser.parse(arguments);
     if (configurations != null && configurations.length > 0) {
-      testConfigurations(configurations);
+      await testConfigurations(configurations);

[Bill Hesse, 2016/04/27 13:54:40]

I still think this is wrong.  It generates exactly the same code as before - the
async-await do exactly nothing.

If we do anything, we should comment that the function does all the testing
asynchronously, and returns a future that we don't wait on.

As you pointed out, we doubt that the future currently returned from
testConfigurations is actually waiting on all async tasks started by all
subsystems.

We should just comment:
// All the testing is carried out asynchronously in tasks created by this call.
// TODO(issue number): Ensure that all tasks complete before the returned future
completes.



Writing await is quite misleading.  What we really should do, is make sure
everything that does anything is waited on, return the final future to main, and
print a message and exit explicitly, and try and find anything that isn't
completed at the point we call exit.  But 

[kustermann, 2016/05/02 10:40:22]

Done - Comment + issue.

     }
   });
 }