Speed up parsing w/ grammar shortcut.

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 "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 377 matching lines @@
   return property != NULL && property->obj()->IsVariableProxy() &&
          property->obj()->AsVariableProxy()->is_this();
 }
 
 
 bool ParserTraits::IsIdentifier(Expression* expression) {
   VariableProxy* operand = expression->AsVariableProxy();
   return operand != NULL && !operand->is_this();
 }
 
+bool ParserTraits::IsEmptyExpression(Expression* expression) {
+  return expression == nullptr;
+}
 
 void ParserTraits::PushPropertyName(FuncNameInferrer* fni,
                                     Expression* expression) {
   if (expression->IsPropertyName()) {
     fni->PushLiteralName(expression->AsLiteral()->AsRawPropertyName());
   } else {
     fni->PushLiteralName(
         parser_->ast_value_factory()->anonymous_function_string());
   }
 }
@@ skipping 6667 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8