Refactor VMTagScope to Thread* rather than Isolate*.

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 8482 matching lines @@
   StoreNonPointer(&raw_ptr()->kind_, value);
 }
 
 
 void Script::set_tokens(const TokenStream& value) const {
   StorePointer(&raw_ptr()->tokens_, value.raw());
 }
 
 
 void Script::Tokenize(const String& private_key) const {
-  Isolate* isolate = Isolate::Current();
-  const TokenStream& tkns = TokenStream::Handle(isolate, tokens());
+  Thread* thread = Thread::Current();
+  Zone* zone = thread->zone();
+  Isolate* isolate = thread->isolate();
+  const TokenStream& tkns = TokenStream::Handle(zone, tokens());
   if (!tkns.IsNull()) {
     // Already tokenized.
     return;
   }
   // Get the source, scan and allocate the token stream.
-  VMTagScope tagScope(isolate, VMTag::kCompileScannerTagId);
+  VMTagScope tagScope(thread, VMTag::kCompileScannerTagId);
   CSTAT_TIMER_SCOPE(isolate, scanner_timer);
-  const String& src = String::Handle(isolate, Source());
+  const String& src = String::Handle(zone, Source());
   Scanner scanner(src, private_key);
-  set_tokens(TokenStream::Handle(isolate,
+  set_tokens(TokenStream::Handle(zone,
                                  TokenStream::New(scanner.GetStream(),
                                                   private_key)));
   INC_STAT(isolate, src_length, src.Length());
 }
 
 
 void Script::SetLocationOffset(intptr_t line_offset,
                                intptr_t col_offset) const {
   ASSERT(line_offset >= 0);
   ASSERT(col_offset >= 0);
@@ skipping 12818 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart