[debugger] fix switch block source positions.

src/parsing/parser-base.h

 // 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.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 5176 matching lines @@
 
   Expect(Token::SWITCH, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   ExpressionT tag = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
   auto switch_statement = factory()->NewSwitchStatement(labels, switch_pos);
 
   {
     BlockState cases_block_state(zone(), &scope_);
-    scope()->set_start_position(scanner()->location().beg_pos);
+    scope()->set_start_position(switch_pos);
     scope()->SetNonlinear();
     typename Types::Target target(this, switch_statement);
 
     bool default_seen = false;
     auto cases = impl()->NewCaseClauseList(4);
     Expect(Token::LBRACE, CHECK_OK);
     while (peek() != Token::RBRACE) {
       // An empty label indicates the default case.
       ExpressionT label = impl()->EmptyExpression();
       if (Check(Token::CASE)) {
@@ skipping 596 matching lines @@
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_CUSTOM
 #undef CHECK_OK_VOID
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H