Revert "[AST] Protect declarations with @_inheritActorContext(always) by a feature flag"

This reverts commit c050e8f.

Author: hamishknight

include/swift/Basic/Features.def

@@ -259,7 +259,6 @@ LANGUAGE_FEATURE(IsolatedConformances, 407, "Global-actor isolated conformances"
 LANGUAGE_FEATURE(ValueGenericsNameLookup, 452, "Value generics appearing as static members for namelookup")
 LANGUAGE_FEATURE(GeneralizedIsSameMetaTypeBuiltin, 465, "Builtin.is_same_metatype with support for noncopyable/nonescapable types")
 SUPPRESSIBLE_LANGUAGE_FEATURE(ABIAttributeSE0479, 479, "@abi attribute on functions, initializers, properties, and subscripts")
-LANGUAGE_FEATURE(AlwaysInheritActorContext, 472, "@_inheritActorContext(always)")
 
 // Swift 6
 UPCOMING_FEATURE(ConciseMagicFile, 274, 6)

lib/AST/FeatureSet.cpp

@@ -624,21 +624,6 @@ static bool usesFeatureExtensibleAttribute(Decl *decl) {
   return decl->getAttrs().hasAttribute<ExtensibleAttr>();
 }
 
-static bool usesFeatureAlwaysInheritActorContext(Decl *decl) {
-  auto *VD = dyn_cast<ValueDecl>(decl);
-  if (!VD)
-    return false;
-
-  if (auto *PL = VD->getParameterList()) {
-    return llvm::any_of(*PL, [&](const ParamDecl *P) {
-      auto *attr = P->getAttrs().getAttribute<InheritActorContextAttr>();
-      return attr && attr->isAlways();
-    });
-  }
-
-  return false;
-}
-
 // ----------------------------------------------------------------------------
 // MARK: - FeatureSet
 // ----------------------------------------------------------------------------