Add suppression to test.dart for flaky content_shell crashes

tools/testing/dart/test_progress.dart

Index: tools/testing/dart/test_progress.dart
diff --git a/tools/testing/dart/test_progress.dart b/tools/testing/dart/test_progress.dart
index 3fdfbf3fa734a438dbf45bd27b96aa0c6ec35b84..c65aa1706164a0d67053f98c6983c789eb2ebd83 100644
--- a/tools/testing/dart/test_progress.dart
+++ b/tools/testing/dart/test_progress.dart
@@ -174,6 +174,30 @@ class ExitCodeSetter extends EventListener {
   }
 }
 
+class IgnoredTestMonitor extends EventListener {
+  static final int maxIgnored = 5;
+
+  int countIgnored = 0;
+
+  void done(TestCase test) {
+    if (test.lastCommandOutput?.result(test) == Expectation.IGNORE) {

[kustermann, 2016/06/24 13:36:44]

Why the "?" ? There should be at least one command output for every test!

[Bill Hesse, 2016/06/27 12:43:15]

I wasn't sure.
Done.

+      countIgnored++;
+      if (countIgnored > maxIgnored) {
+        print("/nMore than $maxIgnored tests were ignored due to flakes in");
+        print("the test infrastructure.  Output of the last ignored test was:");

[kustermann, 2016/06/24 13:36:44]

You should probably add a comment about notifying you about such issues.

[Bill Hesse, 2016/06/27 12:43:15]

Done.

+        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) {