Modify two regression tests to actually fail when failing.

test/mjsunit/regress/regress-1639-2.js

Index: test/mjsunit/regress/regress-1639-2.js
diff --git a/test/mjsunit/regress/regress-1639-2.js b/test/mjsunit/regress/regress-1639-2.js
index c439dd8fffb4f270fcb81e6d89eda77bff4d9a56..01f0dc20485e270facd284e1dcafa5aaf3d2deb2 100644
--- a/test/mjsunit/regress/regress-1639-2.js
+++ b/test/mjsunit/regress/regress-1639-2.js
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -28,6 +28,7 @@
 // Flags: --expose-debug-as debug
 // Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
+var exception = false;
 
 function sendCommand(state, cmd) {
   // Get the debug command processor in paused state.
@@ -79,6 +80,7 @@ function listener(event, exec_state, event_data, data) {
     }
   } catch (e) {
     print(e);
+    exception = true;
   }
 }
 
@@ -91,3 +93,4 @@ function a() {
 // Set a break point and call to invoke the debug event listener.
 Debug.setBreakPoint(a, 0, 0);
 a();
+assertFalse(exception);