Move hashmap.h and hashmap.cc from the 'bin' directory to 'platform' directory so that it can be us…

platform/hashmap.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 BIN_HASHMAP_H_
-#define BIN_HASHMAP_H_
+#ifndef PLATFORM_HASHMAP_H_
+#define PLATFORM_HASHMAP_H_
 
 #include "platform/globals.h"
 
 class HashMap {
  public:
   typedef bool (*MatchFun) (void* key1, void* key2);
 
   static bool SamePointerValue(void* key1, void* key2) {
     return key1 == key2;
   }
@@ skipping 49 matching lines @@
   uint32_t occupancy_;
 
   Entry* map_end() const { return map_ + capacity_; }
   Entry* Probe(void* key, uint32_t hash);
   void Initialize(uint32_t capacity);
   void Resize();
 
   friend class IntSet;  // From hashmap_test.cc
 };
 
-#endif  // BIN_HASHMAP_H_
+#endif  // PLATFORM_HASHMAP_H_