Cleanups: addressed your comments from https://codereview.chromium.org/14962008/

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 4078 matching lines @@
   static const intptr_t kBytesPerElement = kChunkSize;
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
 
   static intptr_t InstanceSize() { return 0; }
 
   static intptr_t InstanceSize(intptr_t len) {
     ASSERT(0 <= len && len <= kMaxElements);
     return RoundedAllocationSize(sizeof(RawBigint) + (len * kBytesPerElement));
   }
 
-  RawBigint* ArithmeticOp(Token::Kind operation, const Bigint& other) const;
-
  protected:
   // Only Integer::NewXXX is allowed to call Bigint::NewXXX directly.
   friend class Integer;
 
+  RawBigint* BigArithmeticOp(Token::Kind operation, const Bigint& other) const;
+
   static RawBigint* New(const String& str, Heap::Space space = Heap::kNew);
 
   // Returns a canonical Bigint object allocated in the old gen space.
   static RawBigint* NewCanonical(const String& str);
 
  private:
   Chunk GetChunkAt(intptr_t i) const {
     return *ChunkAddr(i);
   }
 
@@ skipping 1650 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_