Remove unused code for IsFutureStrictReserved.

src/parsing/parser.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/parsing/parser.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/ast/ast-expression-rewriter.h"
@@ skipping 1627 matching lines @@
   NativeFunctionLiteral* lit =
       factory()->NewNativeFunctionLiteral(name, extension_, kNoSourcePosition);
   return factory()->NewExpressionStatement(
       factory()->NewAssignment(Token::INIT, decl->proxy(), lit,
                                kNoSourcePosition),
       pos);
 }
 
 ZoneList<const AstRawString*>* Parser::DeclareLabel(
     ZoneList<const AstRawString*>* labels, VariableProxy* var, bool* ok) {
+  DCHECK(IsIdentifier(var));
   const AstRawString* label = var->raw_name();
   // TODO(1240780): We don't check for redeclaration of labels
   // during preparsing since keeping track of the set of active
   // labels requires nontrivial changes to the way scopes are
   // structured.  However, these are probably changes we want to
   // make later anyway so we should go back and fix this then.
   if (ContainsLabel(labels, label) || TargetStackContainsLabel(label)) {
     ReportMessage(MessageTemplate::kLabelRedeclaration, label);
     *ok = false;
     return nullptr;
@@ skipping 3842 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8