Remove support for nominal type patterns, which have never been supported in an

official swift release and have bitrotted.

lib/Frontend/CompilerInvocation.cpp

@@ -734,9 +734,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   Opts.UseMalloc |= Args.hasArg(OPT_use_malloc);
 
-  Opts.EnableExperimentalPatterns |=
-    Args.hasArg(OPT_enable_experimental_patterns);
-
   Opts.EnableExperimentalPropertyBehaviors |=
     Args.hasArg(OPT_enable_experimental_property_behaviors);