Suppress get_drt/dartium download if an executable is provided via flag

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 262 matching lines @@
   bool listRecursively() => _listRecursive;
 
   String shellPath() => TestUtils.dartShellFileName(configuration);
 
   List<String> additionalOptions(String filename) => [];
 
   void forEachTest(Function onTest, Map testCache, String globalTempDir(),
                    [Function onDone = null]) {
     // If DumpRenderTree/Dartium is required, and not yet updated,
     // wait for update.
-    var updater = runtimeUpdater(configuration['runtime']);
+    var updater = runtimeUpdater(configuration);
     if (updater !== null && !updater.updated) {
       Expect.isTrue(updater.isActive);
       updater.onUpdated.add(() {
         forEachTest(onTest, testCache, globalTempDir, onDone);
       });
       return;
     }
 
     doTest = onTest;
     doDone = (onDone != null) ? onDone : (() => null);
@@ skipping 1099 matching lines @@
  * $noCrash tests are expected to be flaky but not crash
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
 """;
     print(report);
    }
 }