Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

pkg/analyzer/lib/src/dart/ast/utilities.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library analyzer.src.dart.ast.utilities;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
@@ skipping 2321 matching lines @@
         if (leftOperand is num && rightOperand is num) {
           return leftOperand - rightOperand;
         }
       } else if (node.operator.type == TokenType.PERCENT) {
         // numeric or {@code null}
         if (leftOperand is num && rightOperand is num) {
           return leftOperand.remainder(rightOperand);
         }
       } else if (node.operator.type == TokenType.PLUS) {
         // numeric or {@code null}
-        if ((leftOperand is num && rightOperand is num) ||
-            (leftOperand is String && rightOperand is String)) {
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand + rightOperand;
+        }
+        if (leftOperand is String && rightOperand is String) {
           return leftOperand + rightOperand;
         }
       } else if (node.operator.type == TokenType.STAR) {
         // numeric or {@code null}
         if (leftOperand is num && rightOperand is num) {
           return leftOperand * rightOperand;
         }
       } else if (node.operator.type == TokenType.SLASH) {
         // numeric or {@code null}
         if (leftOperand is num && rightOperand is num) {
@@ skipping 6834 matching lines @@
     if (node.star != null) {
       sink.write("yield* ");
     } else {
       sink.write("yield ");
     }
     safelyVisitNode(node.expression);
     sink.write(";");
     return null;
   }
 }