Don't deallocate the HashTable backing explicitly when it is managed by GC.

Source/wtf/HashTable.h

Index: Source/wtf/HashTable.h
diff --git a/Source/wtf/HashTable.h b/Source/wtf/HashTable.h
index 1289ad48d6c4be60639102583a9b3161c093c0db..30c8bbd5ef55f94a0169bbea561c132d835d5fcd 100644
--- a/Source/wtf/HashTable.h
+++ b/Source/wtf/HashTable.h
@@ -280,6 +280,8 @@ namespace WTF {
         HashTable();
         ~HashTable()
         {
+            if (Allocator::isGarbageCollected)
+                return;
             if (LIKELY(!m_table))
                 return;
             deallocateTable(m_table, m_tableSize);
@@ -887,6 +889,8 @@ namespace WTF {
     template<typename Key, typename Value, typename Extractor, typename HashFunctions, typename Traits, typename KeyTraits, typename Allocator>
     void HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits, Allocator>::deallocateTable(ValueType* table, unsigned size)
     {
+        if (Allocator::isGarbageCollected)
+            return;
         if (Traits::needsDestruction) {
             for (unsigned i = 0; i < size; ++i) {
                 if (!isDeletedBucket(table[i]))