Fix warnings in pkg/analyzer caused by be6a822daff2fae75a480d7da656ab0d9c86512e

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

Index: pkg/analyzer/lib/src/dart/ast/utilities.dart
diff --git a/pkg/analyzer/lib/src/dart/ast/utilities.dart b/pkg/analyzer/lib/src/dart/ast/utilities.dart
index 8ac2c16df693767f4f30d52b213241b5ed254bae..4b9857d26245b8ce8330b8182f061e109cfe61ac 100644
--- a/pkg/analyzer/lib/src/dart/ast/utilities.dart
+++ b/pkg/analyzer/lib/src/dart/ast/utilities.dart
@@ -2339,8 +2339,10 @@ class ConstantEvaluator extends GeneralizingAstVisitor<Object> {
         }
       } 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) {