Add flag to disable capturing stack traces.

utils/tests/pub/test_pub.dart

 // Copyright (c) 2013, 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.
 
 /// Test infrastructure for testing pub. Unlike typical unit tests, most pub
 /// tests are integration tests that stage some stuff on the file system, run
 /// pub, and then validate the results. This library provides an API to build
 /// tests like that.
 library test_pub;
 
@@ skipping 214 matching lines @@
 void solo_integration(String description, void body()) =>
   _integration(description, body, solo_test);
 
 void _integration(String description, void body(), [Function testFn]) {
   testFn(description, () {
     // The windows bots are very slow, so we increase the default timeout.
     if (Platform.operatingSystem == "windows") {
       currentSchedule.timeout = new Duration(seconds: 10);
     }
 
+    // By default, don't capture stack traces since they slow the tests way
+    // down. To debug failing tests, comment this out.
+    currentSchedule.captureStackTraces =
+        new Options().arguments.contains('--trace');
+
     // Ensure the SDK version is always available.
     d.dir(sdkPath, [
       d.file('version', '0.1.2.3')
     ]).create();
 
     _sandboxDir = createTempDir();
     d.defaultRoot = sandboxDir;
     currentSchedule.onComplete.schedule(() => deleteEntry(_sandboxDir),
         'deleting the sandbox directory');
 
@@ skipping 360 matching lines @@
   bool matches(item, MatchState matchState) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }