Revert of Enable per thread heap for database thread

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

 /*
  * Copyright (C) 2007, 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
@@ skipping 69 matching lines @@
 SQLStatementBackend::SQLStatementBackend(SQLStatement* frontend,
     const String& statement, const Vector<SQLValue>& arguments, int permissions)
     : m_frontend(frontend)
     , m_statement(statement.isolatedCopy())
     , m_arguments(arguments)
     , m_hasCallback(m_frontend->hasCallback())
     , m_hasErrorCallback(m_frontend->hasErrorCallback())
     , m_resultSet(SQLResultSet::create())
     , m_permissions(permissions)
 {
-    DCHECK(isMainThread());
-
     m_frontend->setBackend(this);
 }
 
 DEFINE_TRACE(SQLStatementBackend)
 {
     visitor->trace(m_frontend);
     visitor->trace(m_resultSet);
 }
 
 SQLStatement* SQLStatementBackend::frontend()
@@ skipping 131 matching lines @@
     if (lastExecutionFailedDueToQuota())
         m_error = nullptr;
 }
 
 bool SQLStatementBackend::lastExecutionFailedDueToQuota() const
 {
     return m_error && m_error->code() == SQLError::QUOTA_ERR;
 }
 
 } // namespace blink