[debugger] remove step count parameter from prepare step.

test/mjsunit/debug-stepin-builtin.js

Index: test/mjsunit/debug-stepin-builtin.js
diff --git a/test/mjsunit/debug-stepin-builtin.js b/test/mjsunit/debug-stepin-builtin.js
index d9c60611049dfff564865148adf62f570fec5964..f61098045cd8112ea5f5eccebcd2c7dd84b3bd41 100644
--- a/test/mjsunit/debug-stepin-builtin.js
+++ b/test/mjsunit/debug-stepin-builtin.js
@@ -41,14 +41,14 @@ var expected_function_name = null;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        state = 2;
-      } else if (state == 2) {
+      if (state == 3) {
         assertEquals(expected_function_name, event_data.func().name());
         assertEquals(expected_source_line_text,
                      event_data.sourceLineText());
-        state = 3;
+        state = 4;
+      } else {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
       }
     }
   } catch(e) {
@@ -72,7 +72,7 @@ function testStepInArraySlice() {
 state = 1;
 testStepInArraySlice();
 assertNull(exception);
-assertEquals(3, state);
+assertEquals(4, state);
 
 // Get rid of the debug event listener.
 Debug.setListener(null);