[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 661 matching lines @@
   DCHECK_NE(kNoSourcePosition, pos);
   source_position_table_builder_.AddPosition(masm_->pc_offset(), pos, false);
 }
 
 
 void FullCodeGenerator::SetFunctionPosition(FunctionLiteral* fun) {
   RecordPosition(fun->start_position());
 }
 
 
 void FullCodeGenerator::SetReturnPosition(FunctionLiteral* fun) {

[dgozman, 2016/11/08 01:37:13]

Do we have similar problem in other code generation/interpretation systems?

[Yang, 2016/11/08 12:23:33]

Yes, we need this logic in BytecodeArrayBuilder::BytecodeArrayBuilder as well.
Maybe wrap this entire thing into ast.h/ast.cc?

[kozy, 2016/11/08 16:28:45]

Done.

   // 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);
+  bool doesnt_contain_close_brace =
+      IsArrowFunction(fun->kind()) && fun->HasSingleReturnBody();
+  int pos =
+      std::max(fun->start_position(),
+               fun->end_position() - (doesnt_contain_close_brace ? 0 : 1));
   RecordStatementPosition(pos);
   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) {
@@ skipping 1295 matching lines @@
   return info_->has_simple_parameters();
 }
 
 FunctionLiteral* FullCodeGenerator::literal() const { return info_->literal(); }
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8