RequirementMachine: Simplify right hand sides on each iteration of completion

Author: slavapestov

lib/AST/RequirementMachine/RequirementMachine.cpp

@@ -389,10 +389,6 @@ void RequirementMachine::computeCompletion() {
 
     checkCompletionResult();
 
-    // Simplify right hand sides in preparation for building the
-    // property map.
-    System.simplifyRewriteSystem();
-
     // Check invariants.
     System.verify();
 

lib/AST/RequirementMachine/RewriteSystemCompletion.cpp

@@ -431,6 +431,8 @@ RewriteSystem::computeConfluentCompletion(unsigned maxIterations,
       }
     }
 
+    simplifyRewriteSystem();
+
     again = false;
     for (const auto &pair : resolvedCriticalPairs) {
       // Check if we've already done too much work.