Added the clone method. Approved by warren

xpcom/ds/nsHashtable.cpp

@@ -137,6 +137,20 @@ void *nsHashtable::Remove(nsHashKey *aKey) {
   return res;
 }
 
+static PR_CALLBACK PRIntn _hashEnumerateCopy(PLHashEntry *he, PRIntn i, void *arg)
+{
+  nsHashtable *newHashtable = (nsHashtable *)arg;
+  newHashtable->Put((nsHashKey *) he->key, he->value);
+  return HT_ENUMERATE_NEXT;
+}
+
+nsHashtable * nsHashtable::Clone() {
+  nsHashtable *newHashTable = new nsHashtable(hashtable->nentries);
+  
+  PL_HashTableEnumerateEntries(hashtable, _hashEnumerateCopy, newHashTable);
+  return newHashTable;
+}
+
 void nsHashtable::Enumerate(nsHashtableEnumFunc aEnumFunc) {
   PL_HashTableEnumerateEntries(hashtable, _hashEnumerate, aEnumFunc);
 }

xpcom/src/nsHashtable.cpp

@@ -137,6 +137,20 @@ void *nsHashtable::Remove(nsHashKey *aKey) {
   return res;
 }
 
+static PR_CALLBACK PRIntn _hashEnumerateCopy(PLHashEntry *he, PRIntn i, void *arg)
+{
+  nsHashtable *newHashtable = (nsHashtable *)arg;
+  newHashtable->Put((nsHashKey *) he->key, he->value);
+  return HT_ENUMERATE_NEXT;
+}
+
+nsHashtable * nsHashtable::Clone() {
+  nsHashtable *newHashTable = new nsHashtable(hashtable->nentries);
+  
+  PL_HashTableEnumerateEntries(hashtable, _hashEnumerateCopy, newHashTable);
+  return newHashTable;
+}
+
 void nsHashtable::Enumerate(nsHashtableEnumFunc aEnumFunc) {
   PL_HashTableEnumerateEntries(hashtable, _hashEnumerate, aEnumFunc);
 }

xpcom/src/nsHashtable.h

@@ -49,6 +49,7 @@ public:
   void *Put(nsHashKey *aKey, void *aData);
   void *Get(nsHashKey *aKey);
   void *Remove(nsHashKey *aKey);
+  nsHashtable *Clone();
   void Enumerate(nsHashtableEnumFunc aEnumFunc);
 };