Debugger: require debugger to be active when dealing with breaks.

test/mjsunit/debug-liveedit-breakpoints.js

 // Copyright 2010 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 11 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
+Debug.setListener(function(){});
 
 var function_z_text =
 "  function Z() {\n"
 + "    return 'Z';\n" // Breakpoint line ( #6 )
 + "  }\n";
 
 eval(
 "function F25() {\n"
 + "  return 25;\n" // Breakpoint line ( #1 )
 + "}\n"
@@ skipping 62 matching lines @@
 
 for (var i = 0; i < breaks.length; i++) {
   breaks_ids.push(breaks[i].number());
 }
 
 for (var i = 0; i < breaks_ids.length; i++) {
   Debug.clearBreakPoint(breaks_ids[i]);
 }
 
 assertEquals(0, Debug.scriptBreakPoints().length);
+Debug.setListener(null);