Revert of Enable per thread heap for database thread

third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp

Index: third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp
diff --git a/third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp b/third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp
index 6c79f5313df952546bec063bf16ad0c9567d68d5..16b1356c323c272f2de2655d6122d473bcbf85e9 100644
--- a/third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp
+++ b/third_party/WebKit/Source/modules/webdatabase/SQLTransactionCoordinator.cpp
@@ -50,6 +50,7 @@
 
 DEFINE_TRACE(SQLTransactionCoordinator)
 {
+    visitor->trace(m_coordinationInfoMap);
 }
 
 void SQLTransactionCoordinator::processPendingTransactions(CoordinationInfo& info)
@@ -129,8 +130,11 @@
         // transaction is interrupted?" at the top of SQLTransactionBackend.cpp.
         if (info.activeWriteTransaction)
             info.activeWriteTransaction->notifyDatabaseThreadIsShuttingDown();
-        for (auto& it : info.activeReadTransactions) {
-            it->notifyDatabaseThreadIsShuttingDown();
+        for (HeapHashSet<Member<SQLTransactionBackend>>::iterator activeReadTransactionsIterator =
+                     info.activeReadTransactions.begin();
+             activeReadTransactionsIterator != info.activeReadTransactions.end();
+             ++activeReadTransactionsIterator) {
+            (*activeReadTransactionsIterator)->notifyDatabaseThreadIsShuttingDown();
         }
 
         // Clean up transactions that have NOT reached "lockAcquired":