Commented Unassigned: I cannot use RazorGenerator.MVC after upgrade to MVC 5.1.2 [143]

If I won't edit any view I don't have any issue.

But after edit, I cannot compile my project any more:

error CS0103: The name 'Styles' does not exist in the current context
error CS0103: The name 'Scripts' does not exist in the current context

Comments: After reverting back solution to version MVC 5.1.1 all is working again. For some reason System.Web.Optimization; is not added to namespaces after upgrade.