Fix not to show the dialog message when the value of the Local Context is updated

Steps to reproduce the issue.
1. Open Client-Side Calculation Sample Page.
2. Input a number to the "Tax Rate" field.
3. Unfocus the "Tax Rate" field.
4. Change a value of the "Tax Rate" field.
5. Unfocus the "Tax Rate" field.

I think the Local Context doesn't need to checking optimistic lock.