[debugger] remove step count parameter from prepare step.

test/mjsunit/regress/regress-crbug-409614.js

Index: test/mjsunit/regress/regress-crbug-409614.js
diff --git a/test/mjsunit/regress/regress-crbug-409614.js b/test/mjsunit/regress/regress-crbug-409614.js
index 7b27404819faa379e2ac9acb5c2191d12c767909..1a9a77746a16344927a067826ff58b4f5748b8d7 100644
--- a/test/mjsunit/regress/regress-crbug-409614.js
+++ b/test/mjsunit/regress/regress-crbug-409614.js
@@ -10,7 +10,7 @@ var error_count = 0;
 
 function f() {
   return 0;  // Break
-}
+}            // Break
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
@@ -18,7 +18,7 @@ function listener(event, exec_state, event_data, data) {
     if (exec_state.frame(0).sourceLineText().indexOf("Break") <0) {
       error_count++;
     }
-    exec_state.prepareStep(Debug.StepAction.StepIn, 2);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
     f();  // We should not break in this call of f().
   } catch (e) {
     print(e + e.stack);
@@ -29,7 +29,7 @@ function listener(event, exec_state, event_data, data) {
 Debug.setListener(listener);
 
 debugger;  // Break
-f();
+f();       // Break
 
 Debug.setListener(null);  // Break