Remove worker support of Web SQL Database.

Source/modules/webdatabase/AbstractSQLTransaction.h

 /*
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 #define AbstractSQLTransaction_h
 
 #include "modules/webdatabase/SQLTransactionState.h"
 #include "platform/heap/Handle.h"
 #include "wtf/ThreadSafeRefCounted.h"
 
 namespace blink {
 
 class AbstractSQLTransactionBackend;
 
+// FIXME: This abstraction is unnecessary because SQLTransactionSync was
+// removed.
 class AbstractSQLTransaction : public ThreadSafeRefCountedWillBeGarbageCollectedFinalized<AbstractSQLTransaction> {
 public:
     virtual ~AbstractSQLTransaction() { }
     virtual void trace(Visitor*) { }
 
     virtual void requestTransitToState(SQLTransactionState) = 0;
 
     // Used during initialization only.
     virtual bool hasCallback() const = 0;
     virtual bool hasSuccessCallback() const = 0;
     virtual bool hasErrorCallback() const = 0;
     virtual void setBackend(AbstractSQLTransactionBackend*) = 0;
 };
 
 } // namespace blink
 
 #endif // AbstractSQLTransaction_h