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

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 572 matching lines @@
 
   return factory()->NewCallRuntime(context_index, args, pos);
 }
 
 Parser::Parser(ParseInfo* info)
     : ParserBase<Parser>(info->zone(), &scanner_, info->stack_limit(),
                          info->extension(), info->ast_value_factory()),
       scanner_(info->unicode_cache()),
       reusable_preparser_(nullptr),
       original_scope_(nullptr),
+      mode_(PARSE_EAGERLY),  // Lazy mode must be set explicitly.
       target_stack_(nullptr),
       compile_options_(info->compile_options()),
       cached_parse_data_(nullptr),
       total_preparse_skipped_(0),
       parsing_on_main_thread_(true),
       log_(nullptr) {
   // Even though we were passed ParseInfo, we should not store it in
   // Parser - this makes sure that Isolate is not accidentally accessed via
   // ParseInfo during background parsing.
   DCHECK(!info->script().is_null() || info->source_stream() != nullptr ||
@@ skipping 4815 matching lines @@
 
   return final_loop;
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_VOID
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8