Deprecate all diagnostics methods that use strings.

pkg/front_end/lib/src/fasta/testing/validating_instrumentation.dart

 // Copyright (c) 2017, 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.md file.
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:front_end/src/base/instrumentation.dart';
 import 'package:front_end/src/fasta/messages.dart';
 import 'package:front_end/src/fasta/scanner.dart';
@@ skipping 182 matching lines @@
   String _escape(String s) {
     s = s.replaceAll(r'\', r'\\');
     if (s.endsWith('/')) {
       s = '$s ';
     }
     return s.replaceAll('/*', r'/\*').replaceAll('*/', r'*\/');
   }
 
   String _formatProblem(
       Uri uri, int offset, String desc, StackTrace stackTrace) {
-    return format(
+    return deprecated_format(
         uri, offset, '$desc${stackTrace == null ? '' : '\n$stackTrace'}');
   }
 
   String _makeExpectationComment(String property, InstrumentationValue value) {
     return '/*@$property=${_escape(value.toString())}*/';
   }
 
   void _problem(Uri uri, int offset, String desc, _Fix fix) {
     _problems.add(_formatProblem(uri, offset, desc, null));
     _fixes.putIfAbsent(uri, () => []).add(fix);
@@ skipping 27 matching lines @@
       this.property, this.value, this.commentOffset, this.commentLength);
 }
 
 class _Fix {
   final int offset;
   final int length;
   final String replacement;
 
   _Fix(this.offset, this.length, this.replacement);
 }