Deprecate all diagnostics methods that use strings.

pkg/front_end/lib/src/fasta/compile_platform.dart

 // Copyright (c) 2016, 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 fasta.compile_platform;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show exitCode;
 
 import 'compiler_command_line.dart' show CompilerCommandLine;
 
 import 'compiler_context.dart' show CompilerContext;
 
 import 'dill/dill_target.dart' show DillTarget;
 
-import 'errors.dart' show InputError;
+import 'deprecated_problems.dart' show deprecated_InputError;
 
 import 'kernel/kernel_target.dart' show KernelTarget;
 
 import 'kernel/utils.dart' show printProgramText, writeProgramToFile;
 
 import 'ticker.dart' show Ticker;
 
 import 'translate_uri.dart' show TranslateUri;
 
 const int iterations = const int.fromEnvironment("iterations", defaultValue: 1);
 
 Future mainEntryPoint(List<String> arguments) async {
   for (int i = 0; i < iterations; i++) {
     if (i > 0) {
       print("\n");
     }
     try {
       await compilePlatform(arguments);
-    } on InputError catch (e) {
+    } on deprecated_InputError catch (e) {
       exitCode = 1;
-      print(e.format());
+      print(e.deprecated_format());
       return null;
     }
   }
 }
 
 Future compilePlatform(List<String> arguments) async {
   Ticker ticker = new Ticker();
   await CompilerCommandLine.withGlobalOptions("compile_platform", arguments,
       (CompilerContext c) {
     Uri patchedSdk = Uri.base.resolveUri(new Uri.file(c.options.arguments[0]));
@@ skipping 35 matching lines @@
   ticker.logMs("Wrote outline to ${outlineOutput.toFilePath()}");
 
   if (exitCode != 0) return null;
 
   var program = await kernelTarget.buildProgram(verify: c.options.verify);
   if (c.options.dumpIr) printProgramText(program);
   await writeProgramToFile(program, fullOutput);
   ticker.logMs("Wrote program to ${fullOutput.toFilePath()}");
   await kernelTarget.writeDepsFile(fullOutput, deps);
 }