[debugger] remove step count parameter from prepare step.

src/runtime/runtime-debug.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/debug/debug.h"
 #include "src/debug/debug-evaluate.h"
 #include "src/debug/debug-frames.h"
@@ skipping 1194 matching lines @@
 }
 
 
 // Prepare for stepping
 // args[0]: break id for checking execution state
 // args[1]: step action from the enumeration StepAction
 // args[2]: number of times to perform the step, for step out it is the number
 //          of frames to step down.
 RUNTIME_FUNCTION(Runtime_PrepareStep) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
+  DCHECK(args.length() == 2);

[Benedikt Meurer, 2015/12/16 08:03:23]

Nit: DCHECK_EQ(2, args.length())

   CONVERT_NUMBER_CHECKED(int, break_id, Int32, args[0]);
   RUNTIME_ASSERT(isolate->debug()->CheckExecutionState(break_id));
 
-  if (!args[1]->IsNumber() || !args[2]->IsNumber()) {
+  if (!args[1]->IsNumber()) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
   // Get the step action and check validity.
   StepAction step_action = static_cast<StepAction>(NumberToInt32(args[1]));
   if (step_action != StepIn && step_action != StepNext &&
       step_action != StepOut && step_action != StepFrame) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
-  // Get the number of steps.
-  int step_count = NumberToInt32(args[2]);
-  if (step_count < 1) {
-    return isolate->Throw(isolate->heap()->illegal_argument_string());
-  }
-
   // Clear all current stepping setup.
   isolate->debug()->ClearStepping();
 
   // Prepare step.
-  isolate->debug()->PrepareStep(static_cast<StepAction>(step_action),
-                                step_count);
+  isolate->debug()->PrepareStep(static_cast<StepAction>(step_action), 1);
   return isolate->heap()->undefined_value();
 }
 
 
 // Clear all stepping set by PrepareStep.
 RUNTIME_FUNCTION(Runtime_ClearStepping) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 0);
   RUNTIME_ASSERT(isolate->debug()->is_active());
   isolate->debug()->ClearStepping();
@@ skipping 435 matching lines @@
   return Smi::FromInt(isolate->debug()->is_active());
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugBreakInOptimizedCode) {
   UNIMPLEMENTED();
   return NULL;
 }
 }  // namespace internal
 }  // namespace v8