Upload new Dart binaries and re-enable unit tests for test scripts.

tools/testing/dart/http_server.dart

Index: tools/testing/dart/http_server.dart
diff --git a/tools/testing/dart/http_server.dart b/tools/testing/dart/http_server.dart
index 5837e92360c67562a00cde02a38f213a170b73a8..b774319e984fc30be701843158bee2090f62c5b4 100644
--- a/tools/testing/dart/http_server.dart
+++ b/tools/testing/dart/http_server.dart
@@ -31,9 +31,11 @@ main() {
     // Pretend we're running test.dart so that TestUtils doesn't get confused
     // about the "current directory." This is only used if we're trying to run
     // this file independently for local testing.
-    TestUtils.testScriptPath = new Path.fromNative(
-        new Options().script).directoryPath.join(
-        new Path('../../test.dart')).canonicalize().toNativePath();
+    TestUtils.testScriptPath = new Path(new Options().script)
+        .directoryPath
+        .join(new Path('../../test.dart'))
+        .canonicalize()
+        .toNativePath();
     TestingServerRunner.setPackageRootDir({'mode': args['mode'],
         'arch': args['arch'], 'system': Platform.operatingSystem,
         'build_directory': ''});