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

Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp

Index: Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp
diff --git a/Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp b/Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp
index 6b1b7d1d9b949e4426c27213040f9ffaf8e1a6c4..b762038a0f04edffa54f9bade2d7729c1d021a27 100644
--- a/Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp
+++ b/Source/modules/indexeddb/IDBPendingTransactionMonitor.cpp
@@ -31,8 +31,6 @@
 
 namespace blink {
 
-DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(IDBPendingTransactionMonitor)
-
 const char* IDBPendingTransactionMonitor::supplementName()
 {
     return "IDBPendingTransactionMonitor";
@@ -42,14 +40,18 @@
 {
 }
 
-IDBPendingTransactionMonitor& IDBPendingTransactionMonitor::from(WillBeHeapSupplementable<ExecutionContext>& context)
+IDBPendingTransactionMonitor& IDBPendingTransactionMonitor::from(Supplementable<ExecutionContext>& context)
 {
-    IDBPendingTransactionMonitor* supplement = static_cast<IDBPendingTransactionMonitor*>(WillBeHeapSupplement<ExecutionContext>::from(context, supplementName()));
+    IDBPendingTransactionMonitor* supplement = static_cast<IDBPendingTransactionMonitor*>(Supplement<ExecutionContext>::from(context, supplementName()));
     if (!supplement) {
         supplement = new IDBPendingTransactionMonitor();
-        provideTo(context, supplementName(), adoptPtrWillBeNoop(supplement));
+        provideTo(context, supplementName(), adoptPtr(supplement));
     }
     return *supplement;
+}
+
+IDBPendingTransactionMonitor::~IDBPendingTransactionMonitor()
+{
 }
 
 void IDBPendingTransactionMonitor::addNewTransaction(IDBTransaction& transaction)
@@ -65,12 +67,4 @@
     m_transactions.clear();
 }
 
-void IDBPendingTransactionMonitor::trace(Visitor* visitor)
-{
-#if ENABLE(OILPAN)
-    visitor->trace(m_transactions);
-#endif
-    WillBeHeapSupplement<ExecutionContext>::trace(visitor);
-}
-
-} // namespace blink
+};