Don't chain method calls that reach a fixpoint

```
What steps will reproduce the problem?
1. Mark the string ToUpper method as pure

The trace will contain x.ToUpper.ToUpper which is not informative.

We need a way of indicating that a method reaches a fixpoint after a call 
(normalizes?).

```

Original issue reported on code.google.com by `Todd.Sch...@gmail.com` on 18 Mar 2013 at 10:08
