Modify two regression tests to actually fail when failing.

test/mjsunit/regress/regress-1639.js

-// 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:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 10 matching lines @@
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --expose-debug-as debug
 // Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 var breaks = 0;
+var exception = false;
 
 function sendCommand(state, cmd) {
   // Get the debug command processor in paused state.
   var dcp = state.debugCommandProcessor(false);
   var request = JSON.stringify(cmd);
   var response = dcp.processDebugJSONRequest(request);
 }
 
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
       var line = event_data.sourceLineText();
       print('break: ' + line);
 
       assertEquals(-1, line.indexOf('NOBREAK'),
                    "should not break on unexpected lines")
       assertEquals('BREAK ' + breaks, line.substr(-7));
       breaks++;
-      sendCommand(exec_state, {
-        seq: 0,
-        type: "request",
-        command: "continue",
-        arguments: { stepaction: "next" }
-      });
+      if (breaks < 4) {
+        sendCommand(exec_state, {
+          seq: 0,
+          type: "request",
+          command: "continue",
+          arguments: { stepaction: "next" }
+        });
+      }
     }
   } catch (e) {
     print(e);
+    exception = true;
   }
 }
 
 // Add the debug event listener.
 Debug.setListener(listener);
 
 function a(f) {
   if (f) {  // NOBREAK: should not break here!
     try {
       f();
     } catch(e) {
     }
   }
 }  // BREAK 2
 
 function b() {
   c();  // BREAK 0
 }  // BREAK 1
 
 function c() {
   a();
 }
 
 // Set a break point and call to invoke the debug event listener.
 Debug.setBreakPoint(b, 0, 0);
 a(b);
-// BREAK 3
+a(); // BREAK 3
+
+assertFalse(exception);