Revert of [oilpan]: Remove support for tracing off-heap hashmaps.

Source/modules/webdatabase/SQLTransactionCoordinator.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 33 matching lines @@
     return database->stringIdentifier();
 }
 
 SQLTransactionCoordinator::SQLTransactionCoordinator()
     : m_isShuttingDown(false)
 {
 }
 
 void SQLTransactionCoordinator::trace(Visitor* visitor)
 {
-#if ENABLE(OILPAN)
     visitor->trace(m_coordinationInfoMap);
-#endif
 }
 
 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
 {
     if (info.activeWriteTransaction || info.pendingTransactions.isEmpty())
         return;
 
     RefPtrWillBeRawPtr<SQLTransactionBackend> firstPendingTransaction = info.pendingTransactions.first();
     if (firstPendingTransaction->isReadOnly()) {
         do {
@@ skipping 80 matching lines @@
             RefPtrWillBeRawPtr<SQLTransactionBackend> transaction = info.pendingTransactions.first();
             transaction->notifyDatabaseThreadIsShuttingDown();
         }
     }
 
     // Clean up all pending transactions for all databases
     m_coordinationInfoMap.clear();
 }
 
 } // namespace blink