Reenable test.dart to be invoked from dartium checkout

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
diff --git a/tools/testing/dart/test_suite.dart b/tools/testing/dart/test_suite.dart
index ea5fdf0dddc785f33f619f92ee43b0c2b13942e4..43faad8f81f6a395dffcd5d1670a7e9bc6ac04dd 100644
--- a/tools/testing/dart/test_suite.dart
+++ b/tools/testing/dart/test_suite.dart
@@ -666,6 +666,11 @@ class StandardTestSuite implements TestSuite {
       default:
         Expect.fail('unimplemented compiler $compiler');
     }
+    if (executable.endsWith('.dart')) {
+      // Run the compiler script via the Dart VM.
+      args.insertRange(0, 1, executable);
+      executable = TestUtils.dartShellFileName(configuration);
+    }
     return new Command(executable, args);
   }
 
@@ -1257,7 +1262,10 @@ class TestUtils {
   }
 
   static String dartShellFileName(Map configuration) {
-    var name = '${buildDir(configuration)}/${executableName(configuration)}';
+    var name = configuration['dart'];
+    if (name == '') {
+      name = '${buildDir(configuration)}/${executableName(configuration)}';
+    }
     if (!(new File(name)).existsSync() && !configuration['list']) {
       throw "Executable '$name' does not exist";
     }