Handle StepIn for constructors through PrepareStep just like for regular calls

src/full-codegen/full-codegen.cc

 // Copyright 2012 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/full-codegen/full-codegen.h"
 
 #include "src/ast.h"
 #include "src/ast-numbering.h"
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 594 matching lines @@
   if (expr->position() == RelocInfo::kNoPosition) return;
   RecordPosition(masm_, expr->position());
   if (info_->is_debug()) {
     // Always emit a debug break slot before a call.
     DebugCodegen::GenerateSlot(masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_CALL,
                                argc);
   }
 }
 
 
-void FullCodeGenerator::SetConstructCallPosition(Expression* expr) {
+void FullCodeGenerator::SetConstructCallPosition(Expression* expr, int argc) {
   if (expr->position() == RelocInfo::kNoPosition) return;
   RecordPosition(masm_, expr->position());
   if (info_->is_debug()) {
     // Always emit a debug break slot before a construct call.
-    DebugCodegen::GenerateSlot(masm_,
-                               RelocInfo::DEBUG_BREAK_SLOT_AT_CONSTRUCT_CALL);
+    DebugCodegen::GenerateSlot(
+        masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_CONSTRUCT_CALL, argc);
   }
 }
 
 
 void FullCodeGenerator::VisitSuperPropertyReference(
     SuperPropertyReference* super) {
   __ CallRuntime(Runtime::kThrowUnsupportedSuperError, 0);
 }
 
 
@@ skipping 1104 matching lines @@
   return var->mode() == CONST_LEGACY || var->scope()->is_nonlinear() ||
          var->initializer_position() >= proxy->position();
 }
 
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8