Debugger: correctly break in default constructor.

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 542 matching lines @@
   return masm->positions_recorder()->WriteRecordedPositions();
 }
 
 
 void FullCodeGenerator::SetFunctionPosition(FunctionLiteral* fun) {
   RecordPosition(masm_, fun->start_position());
 }
 
 
 void FullCodeGenerator::SetReturnPosition(FunctionLiteral* fun) {
-  RecordStatementPosition(masm_, fun->end_position() - 1);
+  // 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(masm_, 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) {
   if (stmt->position() == RelocInfo::kNoPosition) return;
@@ skipping 1099 matching lines @@
   return var->mode() == CONST_LEGACY || var->scope()->is_nonlinear() ||
          var->initializer_position() >= proxy->position();
 }
 
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8