Migration: make more use of .isNullAware throughout migration engine.

Change-Id: Iffc3f1291574450847402571c36fa7881c84de03
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121961
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

Author: stereotype441

pkg/nnbd_migration/lib/src/edge_builder.dart

@@ -916,8 +916,7 @@ class EdgeBuilder extends GeneralizingAstVisitor<DecoratedType>
   DecoratedType visitMethodInvocation(MethodInvocation node) {
     DecoratedType targetType;
     var target = node.target;
-    var operator = node.operator;
-    bool isNullAware = operator != null && isNullAwareToken(operator.type);
+    bool isNullAware = node.isNullAware;
     var callee = node.methodName.staticElement;
     bool calleeIsStatic = callee is ExecutableElement && callee.isStatic;
     if (node.isCascaded) {
@@ -1043,7 +1042,7 @@ class EdgeBuilder extends GeneralizingAstVisitor<DecoratedType>
   @override
   DecoratedType visitPropertyAccess(PropertyAccess node) {
     return _handlePropertyAccess(node, node.target, node.propertyName,
-        isNullAwareToken(node.operator.type), node.isCascaded);
+        node.isNullAware, node.isCascaded);
   }
 
   @override

pkg/nnbd_migration/lib/src/fix_builder.dart

@@ -218,8 +218,8 @@ abstract class FixBuilder extends GeneralizingAstVisitor<DartType>
       visitSubexpression(node.index, indexContext);
       return AssignmentTargetInfo(readType, writeType);
     } else if (node is PropertyAccess) {
-      return _handleAssignmentTargetForPropertyAccess(node, node.target,
-          node.propertyName, isNullAwareToken(node.operator.type), isCompound);
+      return _handleAssignmentTargetForPropertyAccess(
+          node, node.target, node.propertyName, node.isNullAware, isCompound);
     } else if (node is PrefixedIdentifier) {
       if (node.prefix.staticElement is ImportElement) {
         // TODO(paulberry)
@@ -505,8 +505,8 @@ abstract class FixBuilder extends GeneralizingAstVisitor<DartType>
 
   @override
   DartType visitPropertyAccess(PropertyAccess node) {
-    return _handlePropertyAccess(node, node.target, node.propertyName,
-        isNullAwareToken(node.operator.type));
+    return _handlePropertyAccess(
+        node, node.target, node.propertyName, node.isNullAware);
   }
 
   @override

pkg/nnbd_migration/lib/src/utilities/resolution_utils.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/ast/token.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 
 /// This mixin provides utilities that are useful to visitors implementing
@@ -17,20 +16,6 @@ mixin ResolutionUtils {
   bool isDeclaredOnObject(String name) =>
       (_objectGetNames ??= _computeObjectGetNames()).contains(name);
 
-  /// Determines whether the given property/method access token is null-aware.
-  bool isNullAwareToken(TokenType tokenType) {
-    switch (tokenType) {
-      case TokenType.PERIOD:
-      case TokenType.PERIOD_PERIOD:
-        return false;
-      case TokenType.QUESTION_PERIOD:
-        return true;
-      default:
-        throw new UnimplementedError(
-            'Unexpected token passed to isNullAwareToken: $tokenType');
-    }
-  }
-
   List<String> _computeObjectGetNames() {
     var result = <String>[];
     var objectClass = typeProvider.objectType.element;