Migrate most uses of StackZone(Isolate*) to Thread*.

runtime/vm/parser.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_PARSER_H_
 #define VM_PARSER_H_
 
 #include "include/dart_api.h"
 
 #include "platform/assert.h"
@@ skipping 800 matching lines @@
       ArgumentListNode* arguments);
 
   void AddEqualityNullCheck();
 
   AstNode* BuildClosureCall(intptr_t token_pos,
                             AstNode* closure,
                             ArgumentListNode* arguments);
 
   RawInstance* TryCanonicalize(const Instance& instance, intptr_t token_pos);
 
+  Thread* thread() const { return thread_; }
   Isolate* isolate() const { return isolate_; }
   Zone* zone() const { return thread_->zone(); }
 
   Isolate* isolate_;  // Cached current isolate.
   Thread* thread_;
 
   Script& script_;
   TokenStream::Iterator tokens_iterator_;
   Token::Kind token_kind_;  // Cached token kind for current token.
   Block* current_block_;
@@ skipping 51 matching lines @@
 
   // Indentation of parser trace.
   intptr_t trace_indent_;
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 }  // namespace dart
 
 #endif  // VM_PARSER_H_