Remove unnecessary isolate argument from some visitors

runtime/vm/heap_test.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 "platform/globals.h"
 
 #include "platform/assert.h"
 #include "vm/dart_api_impl.h"
 #include "vm/globals.h"
 #include "vm/heap.h"
@@ skipping 218 matching lines @@
   // so we allow slightly more than expected.
   static const intptr_t kTolerance = 10 * kWordSize;
   EXPECT_LE(expected_size, after - before);
   EXPECT_GT(expected_size + kTolerance, after - before);
   Dart_ExitScope();
 }
 
 
 class FindOnly : public FindObjectVisitor {
  public:
-  FindOnly(Isolate* isolate, RawObject* target)
-      : FindObjectVisitor(isolate), target_(target) {
+  explicit FindOnly(RawObject* target) : target_(target) {
 #if defined(DEBUG)
     EXPECT_GT(Thread::Current()->no_safepoint_scope_depth(), 0);
 #endif
   }
   virtual ~FindOnly() { }
 
   virtual bool FindObject(RawObject* obj) const {
     return obj == target_;
   }
  private:
   RawObject* target_;
 };
 
 
 class FindNothing : public FindObjectVisitor {
  public:
-  FindNothing() : FindObjectVisitor(Isolate::Current()) { }
+  FindNothing() { }
   virtual ~FindNothing() { }
   virtual bool FindObject(RawObject* obj) const { return false; }
 };
 
 
 TEST_CASE(FindObject) {
   Isolate* isolate = Isolate::Current();
   Heap* heap = isolate->heap();
   Heap::Space spaces[2] = {Heap::kOld, Heap::kNew};
   for (size_t space = 0; space < ARRAY_SIZE(spaces); ++space) {
     const String& obj = String::Handle(String::New("x", spaces[space]));
     {
       NoSafepointScope no_safepoint;
-      FindOnly find_only(isolate, obj.raw());
+      FindOnly find_only(obj.raw());
       EXPECT(obj.raw() == heap->FindObject(&find_only));
     }
   }
   {
     NoSafepointScope no_safepoint;
     FindNothing find_nothing;
     EXPECT(Object::null() == heap->FindObject(&find_nothing));
   }
 }
 
 
 TEST_CASE(IterateReadOnly) {
   const String& obj = String::Handle(String::New("x", Heap::kOld));
   Heap* heap = Thread::Current()->isolate()->heap();
   EXPECT(heap->Contains(RawObject::ToAddr(obj.raw())));
   heap->WriteProtect(true, true /* include_code_pages */);
   EXPECT(heap->Contains(RawObject::ToAddr(obj.raw())));
   heap->WriteProtect(false, true /* include_code_pages */);
   EXPECT(heap->Contains(RawObject::ToAddr(obj.raw())));
 }
 
 }  // namespace dart.