Fixes memory leaks in the eventhandler

runtime/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 PLATFORM_HASHMAP_H_
 #define PLATFORM_HASHMAP_H_
 
 #include "platform/globals.h"
 
 namespace dart {
 
 class HashMap {
  public:
   typedef bool (*MatchFun) (void* key1, void* key2);
 
+  typedef void (*ClearFun) (void* value);
+
   static bool SamePointerValue(void* key1, void* key2) {
     return key1 == key2;
   }
 
   static uint32_t StringHash(char* key) {
     uint32_t hash_ = 0;
     if (key == NULL) return hash_;
     int len = strlen(key);
     for (int i = 0; i < len; i++) {
       hash_ += key[i];
@@ skipping 15 matching lines @@
   // initial_capacity is the size of the initial hash map;
   // it must be a power of 2 (and thus must not be 0).
   HashMap(MatchFun match, uint32_t initial_capacity);
 
   ~HashMap();
 
   // HashMap entries are (key, value, hash) triplets.
   // Some clients may not need to use the value slot
   // (e.g. implementers of sets, where the key is the value).
   struct Entry {
+    Entry() : key(NULL), value(NULL), hash(0) {}
     void* key;
     void* value;
     uint32_t hash;  // The full hash value for key.
   };
 
   // If an entry with matching key is found, Lookup()
   // returns that entry. If no matching entry is found,
   // but insert is set, a new entry is inserted with
   // corresponding key, key hash, and NULL value.
   // Otherwise, NULL is returned.
   Entry* Lookup(void* key, uint32_t hash, bool insert);
 
   // Removes the entry with matching key.
   void Remove(void* key, uint32_t hash);
 
-  // Empties the hash map (occupancy() == 0).
-  void Clear();
+  // Empties the hash map (occupancy() == 0), and calls the function 'clear' on
+  // each of the values if given.
+  void Clear(ClearFun clear = NULL);
+
+  // The number of entries stored in the table.
+  intptr_t size() const { return occupancy_; }
 
   // The capacity of the table. The implementation
   // makes sure that occupancy is at most 80% of
   // the table capacity.
   intptr_t capacity() const { return capacity_; }
 
   // Iteration
   //
   // for (Entry* p = map.Start(); p != NULL; p = map.Next(p)) {
   //   ...
@@ skipping 14 matching lines @@
   Entry* Probe(void* key, uint32_t hash);
   void Initialize(uint32_t capacity);
   void Resize();
 
   friend class IntSet;  // From hashmap_test.cc
 };
 
 }  // namespace dart
 
 #endif  // PLATFORM_HASHMAP_H_