[parser] Only track parsing-mode (and possibly switch to the preparser) in the parser

src/parsing/preparser.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_PREPARSER_H
 #define V8_PARSING_PREPARSER_H
 
 #include "src/ast/scopes.h"
 #include "src/parsing/parser-base.h"
 
@@ skipping 893 matching lines @@
   // All ParseXXX functions take as the last argument an *ok parameter
   // which is set to false if parsing failed; it is unchanged otherwise.
   // By making the 'exception handling' explicit, we are forced to check
   // for failure at the call sites.
 
   V8_INLINE PreParserStatementList ParseEagerFunctionBody(
       PreParserIdentifier function_name, int pos,
       const PreParserFormalParameters& parameters, FunctionKind kind,
       FunctionLiteral::FunctionType function_type, bool* ok);
 
+  // Indicates that we won't switch from the preparser to the preparser; we'll
+  // just stay where we are.
   bool AllowsLazyParsingWithoutUnresolvedVariables() const { return false; }
+  bool parse_lazily() const { return false; }
 
   V8_INLINE LazyParsingResult SkipFunction(
       FunctionKind kind, DeclarationScope* function_scope, int* num_parameters,
       int* function_length, bool* has_duplicate_parameters,
       int* materialized_literal_count, int* expected_property_count,
       bool is_inner_function, bool may_abort, bool* ok) {
     UNREACHABLE();
     return kLazyParsingComplete;
   }
   Expression ParseFunctionLiteral(
@@ skipping 591 matching lines @@
 PreParserExpression PreParser::SpreadCallNew(PreParserExpression function,
                                              PreParserExpressionList args,
                                              int pos) {
   return factory()->NewCallNew(function, args, pos);
 }
 
 PreParserStatementList PreParser::ParseEagerFunctionBody(
     PreParserIdentifier function_name, int pos,
     const PreParserFormalParameters& parameters, FunctionKind kind,
     FunctionLiteral::FunctionType function_type, bool* ok) {
-  ParsingModeScope parsing_mode(this, PARSE_EAGERLY);
   PreParserStatementList result;
 
   Scope* inner_scope = scope();
   if (!parameters.is_simple) inner_scope = NewScope(BLOCK_SCOPE);
 
   {
     BlockState block_state(&scope_state_, inner_scope);
     ParseStatementList(result, Token::RBRACE, ok);
     if (!*ok) return PreParserStatementList();
   }
@@ skipping 11 matching lines @@
     function_state_->NextMaterializedLiteralIndex();
     function_state_->NextMaterializedLiteralIndex();
   }
   return EmptyExpression();
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PREPARSER_H