[inspector] fix positions for single expression arrow function

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/ast-numbering.h"
 #include "src/ast/ast.h"
 #include "src/ast/prettyprinter.h"
 #include "src/ast/scopes.h"
@@ skipping 664 matching lines @@
 
 
 void FullCodeGenerator::SetFunctionPosition(FunctionLiteral* fun) {
   RecordPosition(fun->start_position());
 }
 
 
 void FullCodeGenerator::SetReturnPosition(FunctionLiteral* fun) {
   // For default constructors, start position equals end position, and there
   // is no source code besides the class literal.
-  int pos = std::max(fun->start_position(), fun->end_position() - 1);
-  RecordStatementPosition(pos);
+  RecordStatementPosition(fun->return_position());
   if (info_->is_debug()) {
     // Always emit a debug break slot before a return.
     DebugCodegen::GenerateSlot(masm_, RelocInfo::DEBUG_BREAK_SLOT_AT_RETURN);
   }
 }
 
 
 void FullCodeGenerator::SetStatementPosition(
     Statement* stmt, FullCodeGenerator::InsertBreak insert_break) {
   if (stmt->position() == kNoSourcePosition) return;
@@ skipping 1294 matching lines @@
   return info_->has_simple_parameters();
 }
 
 FunctionLiteral* FullCodeGenerator::literal() const { return info_->literal(); }
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8