Simplify ReferenceResolver creation.

Change-Id: I1445b80d9453dc8d1df9f0a3bc850bda11e109f7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/207781
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/summary2/function_type_builder.dart

@@ -190,6 +190,7 @@ class FunctionTypeBuilder extends TypeBuilder {
       } else if (isNNBD) {
         nullabilitySuffix = NullabilitySuffix.none;
       } else {
+        // TODO(scheglov) legacy?
         nullabilitySuffix = NullabilitySuffix.question;
       }
 

pkg/analyzer/lib/src/summary2/library_builder.dart

@@ -2,7 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart' as ast;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/ast/ast.dart' as ast;
@@ -161,7 +160,7 @@ class LibraryBuilder {
 
   void resolveTypes(NodesToBuildType nodesToBuildType) {
     for (var linkingUnit in units) {
-      var resolver = _newTypeReferenceResolver(nodesToBuildType, linkingUnit);
+      var resolver = ReferenceResolver(linker, nodesToBuildType, element);
       linkingUnit.node.accept(resolver);
     }
   }
@@ -212,7 +211,7 @@ class LibraryBuilder {
             {
               var nodesToBuildType = NodesToBuildType();
               var resolver =
-                  _newTypeReferenceResolver(nodesToBuildType, linkingUnit);
+                  ReferenceResolver(linker, nodesToBuildType, element);
               for (var newMember in newMembers) {
                 newMember.accept(resolver);
               }
@@ -258,21 +257,6 @@ class LibraryBuilder {
     }
   }
 
-  ReferenceResolver _newTypeReferenceResolver(
-    NodesToBuildType nodesToBuildType,
-    LinkingUnit linkingUnit,
-  ) {
-    /// TODO(scheglov) Do we need all these parameters?
-    return ReferenceResolver(
-      linker,
-      nodesToBuildType,
-      linker.elementFactory,
-      element,
-      linkingUnit.reference,
-      linkingUnit.node.featureSet.isEnabled(Feature.non_nullable),
-    );
-  }
-
   static void build(Linker linker, LinkInputLibrary inputLibrary) {
     var elementFactory = linker.elementFactory;
 

pkg/analyzer/lib/src/summary2/reference_resolver.dart

@@ -14,10 +14,8 @@ import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_system.dart';
 import 'package:analyzer/src/summary2/function_type_builder.dart';
 import 'package:analyzer/src/summary2/link.dart';
-import 'package:analyzer/src/summary2/linked_element_factory.dart';
 import 'package:analyzer/src/summary2/linking_node_scope.dart';
 import 'package:analyzer/src/summary2/named_type_builder.dart';
-import 'package:analyzer/src/summary2/reference.dart';
 import 'package:analyzer/src/summary2/types_builder.dart';
 
 /// Recursive visitor of [LinkedNode]s that resolves explicit type annotations
@@ -33,8 +31,6 @@ class ReferenceResolver extends ThrowingAstVisitor<void> {
   final Linker linker;
   final TypeSystemImpl _typeSystem;
   final NodesToBuildType nodesToBuildType;
-  final LinkedElementFactory elementFactory;
-  final Reference unitReference;
 
   /// Indicates whether the library is opted into NNBD.
   final bool isNNBD;
@@ -44,12 +40,10 @@ class ReferenceResolver extends ThrowingAstVisitor<void> {
   ReferenceResolver(
     this.linker,
     this.nodesToBuildType,
-    this.elementFactory,
     LibraryElementImpl libraryElement,
-    this.unitReference,
-    this.isNNBD,
   )   : _typeSystem = libraryElement.typeSystem,
-        scope = libraryElement.scope;
+        scope = libraryElement.scope,
+        isNNBD = libraryElement.isNonNullableByDefault;
 
   @override
   void visitBlockFunctionBody(BlockFunctionBody node) {}