Remove unused private member variables found by clang -Wunused-private-field

test/cctest/test-heap-profiler.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 //
 // Tests for heap profiler
 
 #include <ctype.h>
 
 #include "v8.h"
 
 #include "cctest.h"
 #include "hashmap.h"
@@ skipping 997 matching lines @@
       }
     }
     CHECK(false);
     return NULL;
   }
 
   static i::List<TestRetainedObjectInfo*> instances;
 
  private:
   bool disposed_;
-  int category_;
   int hash_;
   const char* group_label_;
   const char* label_;
   intptr_t element_count_;
   intptr_t size_;
 };
 
 
 i::List<TestRetainedObjectInfo*> TestRetainedObjectInfo::instances;
 }
@@ skipping 645 matching lines @@
   const v8::HeapGraphNode* map =
       GetProperty(global_object, v8::HeapGraphEdge::kInternal, "map");
   CHECK_NE(NULL, map);
   const v8::HeapGraphNode* own_descriptors = GetProperty(
       map, v8::HeapGraphEdge::kInternal, "descriptors");
   CHECK_NE(NULL, own_descriptors);
   const v8::HeapGraphNode* own_transitions = GetProperty(
       map, v8::HeapGraphEdge::kInternal, "transitions");
   CHECK_EQ(NULL, own_transitions);
 }