Wraps ILGenerator with code that tracks the current IL offset as instructions are emitted into the IL stream. We can conditionally compile this for non-Dev10 release only (using //#ifdef MICROSOFT_SCRIPTING) as soon as Dev10 feature request (http://vstfdevdiv:8080/WorkItemTracking/WorkItem.aspx?artifactMoniker=599427) gets implemented.
 internal override void MarkSequencePoint(LambdaExpression method, MethodBase methodBase, ILGenerator ilg, DebugInfoExpression sequencePoint) {
     MethodBuilder builder = methodBase as MethodBuilder;
     if (builder != null) {
         ilg.MarkSequencePoint(GetSymbolWriter(builder, sequencePoint.Document), sequencePoint.StartLine, sequencePoint.StartColumn, sequencePoint.EndLine, sequencePoint.EndColumn);
     }
 }
        internal override void MarkSequencePoint(LambdaExpression method, MethodBase methodBase, ILGenerator ilg, DebugInfoExpression sequencePoint)
        {
            MethodBuilder builder = methodBase as MethodBuilder;

            if (builder != null)
            {
                ilg.MarkSequencePoint(GetSymbolWriter(builder, sequencePoint.Document), sequencePoint.StartLine, sequencePoint.StartColumn, sequencePoint.EndLine, sequencePoint.EndColumn);
            }
        }