[debugger] remove step count parameter from prepare step.

test/mjsunit/debug-stepout-scope-part1.js

 // Copyright 2011 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 26 matching lines @@
     // Access scope details.
     var scope_count = exec_state.frame().scopeCount();
     for (var i = 0; i < scope_count; i++) {
       var scope = exec_state.frame().scope(i);
       // assertTrue(scope.isScope());
       scope.scopeType();
       scope.scopeObject();
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 
 Debug.setListener(listener);
 
 
 function test1() {
   debugger;
   with ({x:1}) {
     x = 2;
@@ skipping 121 matching lines @@
 } catch(e) {
   nop();
 }
 
 
 function nop() {}
 
 
 // With block as the last(!) statement in global code.
 with ({}) { debugger; }