Oilpan:Allow custom handling of classes that contain weak pointers that are embedded in collections.

Source/wtf/HashTable.h

Index: Source/wtf/HashTable.h
diff --git a/Source/wtf/HashTable.h b/Source/wtf/HashTable.h
index 9b3bb19daa9446246e9ba12f8e6cf4e824a3c5c0..76ecb4844d9d2d89430a4d1d587098655c1e04f2 100644
--- a/Source/wtf/HashTable.h
+++ b/Source/wtf/HashTable.h
@@ -1120,7 +1120,7 @@ namespace WTF {
                 // strongly).
                 for (typename HashTableType::ValueType* element = table->m_table + table->m_tableSize - 1; element >= table->m_table; element--) {
                     if (!HashTableType::isEmptyOrDeletedBucket(*element)) {
-                        if (Allocator::hasDeadMember(visitor, *element)) {
+                        if (Traits::shouldRemoveFromCollection(visitor, *element)) {
                             table->registerModification();
                             HashTableType::deleteBucket(*element); // Also calls the destructor.
                             table->m_deletedCount++;