Retry DRT if we crash with core dump.

tools/testing/dart/test_runner.dart

Index: tools/testing/dart/test_runner.dart
===================================================================
--- tools/testing/dart/test_runner.dart	(revision 4341)
+++ tools/testing/dart/test_runner.dart	(working copy)
@@ -213,9 +213,10 @@
     // If the browser test failed, it may have been because DumpRenderTree
     // and the virtual framebuffer X server didn't hook up.
     for (String line in stderr) {
-      if (line.contains('Gtk-WARNING **: cannot open display: :99')) {
-        // If we get the X server error, return the expected value
-        // We cannot restart the test from here.  Issue dart:1135 is filed.
+      if (line.contains('Gtk-WARNING **: cannot open display: :99') ||
+        line.contains('Failed to run command. return code=1')) {
+        // If we get the X server error, or DRT crashes with a core dump, retry
+        // the test. 
         requestRetry = true;
         return true;
       }