Fixes memory leaks in the eventhandler

runtime/platform/hashmap.h

Index: runtime/platform/hashmap.h
diff --git a/runtime/platform/hashmap.h b/runtime/platform/hashmap.h
index d5a02930f45f4c780c89229ba293f48aba1c231b..b5c938f4c42077414f5bc9d519fed1179a99f603 100644
--- a/runtime/platform/hashmap.h
+++ b/runtime/platform/hashmap.h
@@ -13,6 +13,8 @@ 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;
   }
@@ -48,6 +50,7 @@ class HashMap {
   // 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.
@@ -63,8 +66,12 @@ class HashMap {
   // 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