[debugger] simplify stepping logic.

test/cctest/test-debug.cc

 // Copyright 2012 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 323 matching lines @@
     CompileRunChecked(isolate, "debug.Debug.setBreakOnUncaughtException()");
   } else {
     CompileRunChecked(isolate, "debug.Debug.clearBreakOnUncaughtException()");
   }
 }
 
 
 // Prepare to step to next break location.
 static void PrepareStep(StepAction step_action) {
   v8::internal::Debug* debug = CcTest::i_isolate()->debug();
-  debug->PrepareStep(step_action, 1);
+  debug->PrepareStep(step_action);
 }
 
 
 static void ClearStepping() { CcTest::i_isolate()->debug()->ClearStepping(); }
 
 
 // This function is in namespace v8::internal to be friend with class
 // v8::internal::Debug.
 namespace v8 {
 namespace internal {
@@ skipping 7694 matching lines @@
   CompileRun("function foo() {}; foo();");
   --after_compile_handler_depth;
 }
 
 
 TEST(NoInterruptsInDebugListener) {
   DebugLocalContext env;
   v8::Debug::SetDebugEventListener(env->GetIsolate(), NoInterruptsOnDebugEvent);
   CompileRun("void(0);");
 }