Refactor VMTagScope to Thread* rather than Isolate*.

runtime/vm/regexp_parser.cc

 // Copyright (c) 2014, 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.
 
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 #include "vm/regexp_parser.h"
 
 namespace dart {
 
@@ skipping 199 matching lines @@
       multiline_(multiline),
       simple_(false),
       contains_anchor_(false),
       is_scanned_for_captures_(false),
       failed_(false) {
   Advance();
 }
 
 
 bool RegExpParser::ParseFunction(ParsedFunction *parsed_function) {
-  VMTagScope tagScope(Thread::Current()->isolate(),
+  VMTagScope tagScope(parsed_function->thread(),
                       VMTag::kCompileParseRegExpTagId);
   Zone* zone = parsed_function->zone();
   JSRegExp& regexp = JSRegExp::Handle(parsed_function->function().regexp());
 
   const String& pattern = String::Handle(regexp.pattern());
   const bool multiline = regexp.is_multi_line();
 
   RegExpCompileData* compile_data = new(zone) RegExpCompileData();
   if (!RegExpParser::ParseRegExp(pattern, multiline, compile_data)) {
     // Parsing failures are handled in the JSRegExp factory constructor.
@@ skipping 840 matching lines @@
           String::Concat(result->error, input));
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, message);
 
     Exceptions::ThrowByType(Exceptions::kFormat, args);
   }
   return !parser.failed();
 }
 
 }  // namespace dart