Add suppression to test.dart for flaky content_shell crashes

tools/testing/dart/test_progress.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.
 
 library test_progress;
 
 import "dart:async";
 import "dart:io";
 import "dart:io" as io;
 import "dart:convert" show JSON;
@@ skipping 156 matching lines @@
 }
 
 class ExitCodeSetter extends EventListener {
   void done(TestCase test) {
     if (test.unexpectedOutput) {
       io.exitCode = 1;
     }
   }
 }
 
+class IgnoredTestMonitor extends EventListener {
+  static final int maxIgnored = 5;
+
+  int countIgnored = 0;
+
+  void done(TestCase test) {
+    if (test.lastCommandOutput.result(test) == Expectation.IGNORE) {
+      countIgnored++;
+      if (countIgnored > maxIgnored) {
+        print("/nMore than $maxIgnored tests were ignored due to flakes in");
+        print("the test infrastructure. Notify whesse@google.com.");
+        print("Output of the last ignored test was:");
+        print(_buildFailureOutput(test));
+        exit(1);
+      }
+    }
+  }
+
+  void allDone() {
+    if (countIgnored > 0) {
+      print("Ignored $countIgnored tests due to flaky infrastructure");
+    }
+  }
+}
+
 class FlakyLogWriter extends EventListener {
   void done(TestCase test) {
     if (test.isFlaky && test.result != Expectation.PASS) {
       var buf = new StringBuffer();
       for (var l in _buildFailureOutput(test)) {
         buf.write("$l\n");
       }
       _appendToFlakyFile(buf.toString());
     }
   }
@@ skipping 477 matching lines @@
       return new VerboseProgressIndicator(startTime);
     case 'status':
       return new ProgressIndicator(startTime);
     case 'buildbot':
       return new BuildbotProgressIndicator(startTime);
     default:
       assert(false);
       break;
   }
 }