[debugger] remove step count parameter from prepare step.

test/mjsunit/debug-stepin-property-function-call.js

 // Copyright 2014 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 20 matching lines @@
 
 var exception = null;
 var state = 1;
 
 // Simple debug event handler which first time will cause 'step in' action
 // to get into g.call and than check that execution is stopped inside
 // function 'g'.
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-        state = 2;
-      } else if (state == 2) {
+      if (state < 4) {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
+      } else {
         assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0,
           "source line: \"" + event_data.sourceLineText() + "\"");
-        state = 3;
+        state = 5;
       }
     }
   } catch(e) {
     print("Exception: " + e);
     exception = e;
   }
 };
 
 // Add the debug event listener.
 Debug.setListener(listener);
@@ skipping 78 matching lines @@
 var functionsCalled = 0;
 for (var n in this) {
   if (n.substr(0, 4) != 'test' || typeof this[n] !== "function") {
     continue;
   }
   state = 1;
   print("Running " + n + "...");
   this[n]();
   ++functionsCalled;
   assertNull(exception, n);
-  assertEquals(3, state, n);
+  assertEquals(5, state, n);
   assertEquals(functionsCalled, count, n);
 }
 
 assertEquals(11, functionsCalled);
 
 // Get rid of the debug event listener.
 Debug.setListener(null);