Added support for isolate unhandled exceptions.

tests/isolate/isolate.status

Index: tests/isolate/isolate.status
diff --git a/tests/isolate/isolate.status b/tests/isolate/isolate.status
index 5d7fc3e3ca44b88e38c8c874df13e5f33c87dae6..67038fc29015dab3cbbd18e3edeb666bc2c97a55 100644
--- a/tests/isolate/isolate.status
+++ b/tests/isolate/isolate.status
@@ -4,12 +4,14 @@
 
 [ $runtime == vm ]
 isolate2_negative_test: Skip  # Need to resolve correct behaviour.
+isolate3_negative_test: Skip  # test depends on isolate error exiting process.
 serialization_test: Skip  # tests dart2js-specific serialization code
 spawn_uri_test: Fail, OK # test uses a ".js" suffix that is bogus on vm.
 compute_this_script_browser_test: Skip # browser specific test
 timer_not_available_test: Fail, OK # only meant to test when there is no way to
                                    # implement timer (currently only in d8)
 timer_isolate_test: Skip # See Issue 4997
+unresolved_ports_negative_test: Skip # See Issue 6839
 
 [ $compiler == none && $runtime == drt ]
 serialization_test: Skip  # tests dart2js-specific serialization code
@@ -68,7 +70,7 @@ v2*: Skip
 [ $runtime == opera ]
 multiple_timer_test: Pass, Fail
 isolate2_negative_test: Skip # Timeout.
-unresolved_ports_negative_test: Skip # Timeout.
+unresolved_ports_negative_test: Skip # See Issue 6839
 
 [ $runtime == opera && $system == windows]
 # TODO(efortuna): Investigate.