Fix a bug when top level break points fall into the last function in script.

test/mjsunit/debug-setbreakpoint.js

 // Copyright 2008 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
@@ skipping 98 matching lines @@
 
     testArguments(dcp, '{"type":"scriptId","target":' + f_script_id + ',"line":' + f_line + '}', true, false);
     testArguments(dcp, '{"type":"scriptId","target":' + g_script_id + ',"line":' + g_line + '}', true, false);
     testArguments(dcp, '{"type":"scriptId","target":' + h_script_id + ',"line":' + h_line + '}', true, false);
 
     mirror = debug.MakeMirror(f);
     testArguments(dcp, '{"type":"handle","target":' + mirror.handle() + '}', true, false);
     mirror = debug.MakeMirror(o.a);
     testArguments(dcp, '{"type":"handle","target":' + mirror.handle() + '}', true, false);
 
-    testArguments(dcp, '{"type":"script","target":"sourceUrlScript","line":1}', true, true);
+    testArguments(dcp, '{"type":"script","target":"sourceUrlScript","line":0}', true, true);
 
     // Indicate that all was processed.
     listenerComplete = true;
   }
   } catch (e) {
     exception = e
   };
 };
 
 // Add the debug event listener.
@@ skipping 53 matching lines @@
 Debug.setListener(breakListener);
 
 sourceUrlFunc();
 
 assertTrue(breakListenerCalled, "Break listener not called on breakpoint set by sourceURL");
 
 // Set a break point on a line with the comment, and check that actual position
 // is the next line after the comment.
 var number = Debug.setScriptBreakPointById(g_script_id, g_line + 1);
 assertEquals(g_line + 2, Debug.findBreakPoint(number).actual_location.line);