Remove unnecessary isolate argument from some visitors

runtime/vm/compiler_stats.cc

 // Copyright (c) 2011, 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/compiler_stats.h"
 
 #include "vm/flags.h"
 #include "vm/log.h"
 #include "vm/object_graph.h"
 #include "vm/object_store.h"
 #include "vm/timer.h"
 
 
 namespace dart {
 
 DEFINE_FLAG(bool, compiler_stats, false, "Compiler stat counters.");
 DEFINE_FLAG(bool, compiler_benchmark, false,
             "Compiler stat counters for benchmark.");
 
 
 class TokenStreamVisitor : public ObjectVisitor {
  public:
-  TokenStreamVisitor(Isolate* isolate, CompilerStats* compiler_stats)
-      : ObjectVisitor(isolate),
-        obj_(Object::Handle()),
+  explicit TokenStreamVisitor(CompilerStats* compiler_stats)
+      : obj_(Object::Handle()),
         stats_(compiler_stats) {
   }
 
   void VisitObject(RawObject* raw_obj) {
     if (raw_obj->IsFreeListElement()) {
       return;
     }
     obj_ = raw_obj;
     if (obj_.GetClassId() == TokenStream::kClassId) {
       TokenStream::Iterator tkit(TokenStream::Cast(obj_),
@@ skipping 70 matching lines @@
   va_start(args, format);
   stats->text = zone->VPrint(format, args);
   va_end(args);
 }
 
 
 void CompilerStats::Update() {
   // Traverse the heap and compute number of tokens in all
   // TokenStream objects.
   num_tokens_total = 0;
-  TokenStreamVisitor visitor(isolate_, this);
+  TokenStreamVisitor visitor(this);
   isolate_->heap()->IterateObjects(&visitor);
   Dart::vm_isolate()->heap()->IterateObjects(&visitor);
 }
 
 
 void CompilerStats::EnableBenchmark() {
   FLAG_compiler_stats = true;
   use_benchmark_output = true;
 }
 
@@ skipping 157 matching lines @@
   log.Print("  VarDesc size:          %" Pd64 " KB\n", vardesc_size / 1024);
   log.Flush();
   char* stats_text = text;
   text = NULL;
   return stats_text;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart