Remove the post-inliner runs of the devirtualization pass.

They have no effect. The pre-inliner run may be enabling some
specialization at this point. If it turns out that is not the case, I'll
remove those runs and delete the pass.

Swift SVN r26792

lib/SILPasses/Passes.cpp

@@ -275,7 +275,6 @@ void swift::runSILOptimizationPasses(SILModule &Module) {
   PM.addClosureSpecializer();
 
   // Insert inline caches for virtual calls.
-  PM.addDevirtualizer();
   PM.addInlineCaches();
 
   // Optimize function signatures if we are asked to.
@@ -306,7 +305,6 @@ void swift::runSILOptimizationPasses(SILModule &Module) {
   PM.addGlobalLoadStoreOpts();
   PM.addLateCodeMotion();
   PM.addGlobalARCOpts();
-  PM.addDevirtualizer();
 
   PM.runOneIteration();
   PM.resetAndRemoveTransformations();