[Runtime] Clean up verifyMangledNameRoundtrip comment.

Author: mikeash

stdlib/public/runtime/Metadata.cpp

@@ -5648,13 +5648,8 @@ static bool referencesAnonymousContext(Demangle::Node *node) {
 }
 
 void swift::verifyMangledNameRoundtrip(const Metadata *metadata) {
-  // Enable verification when a special environment variable is set.
-  // Some metatypes crash when going through the mangler or demangler. A
-  // lot of tests currently trigger those crashes, resulting in failing
-  // tests which are still usefully testing something else. This
-  // variable lets us easily turn on verification to find and fix these
-  // bugs. Remove this and leave it permanently on once everything works
-  // with it enabled.
+  // Enable verification when a special environment variable is set. This helps
+  // us stress test the mangler/demangler and type lookup machinery.
   if (!swift::runtime::environment::SWIFT_ENABLE_MANGLED_NAME_VERIFICATION())
     return;