Deprecate all diagnostics methods that use strings.

pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.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.kernel_field_builder;
 
 import 'package:front_end/src/fasta/kernel/body_builder.dart' show BodyBuilder;
 
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart'
     show KernelField;
 
 import 'package:front_end/src/fasta/parser/parser.dart' show Parser;
 
 import 'package:front_end/src/scanner/token.dart' show Token;
 
 import 'package:front_end/src/fasta/builder/class_builder.dart'
     show ClassBuilder;
 
 import 'package:front_end/src/fasta/source/source_library_builder.dart'
     show SourceLibraryBuilder;
 
 import 'package:front_end/src/fasta/type_inference/type_inference_listener.dart'
     show TypeInferenceListener;
 
 import 'package:kernel/ast.dart'
     show DartType, Expression, Field, Name, NullLiteral;
 
-import '../errors.dart' show internalError;
+import '../deprecated_problems.dart' show deprecated_internalProblem;
 
 import 'kernel_builder.dart'
     show Builder, FieldBuilder, KernelTypeBuilder, MetadataBuilder;
 
 class KernelFieldBuilder extends FieldBuilder<Expression> {
   final KernelField field;
   final List<MetadataBuilder> metadata;
   final KernelTypeBuilder type;
   final Token initializerTokenForInference;
   final bool hasInitializer;
 
   KernelFieldBuilder(
       this.metadata,
       this.type,
       String name,
       int modifiers,
       Builder compilationUnit,
       int charOffset,
       this.initializerTokenForInference,
       this.hasInitializer)
       : field = new KernelField(null, fileUri: compilationUnit?.relativeFileUri)
           ..fileOffset = charOffset,
         super(name, modifiers, compilationUnit, charOffset);
 
   void set initializer(Expression value) {
     if (!hasInitializer && value is! NullLiteral && !isConst && !isFinal) {
-      internalError("Attempt to set initializer on field without initializer.");
+      deprecated_internalProblem(
+          "Attempt to set initializer on field without initializer.");
     }
     field.initializer = value..parent = field;
   }
 
   bool get isEligibleForInference =>
       type == null && (hasInitializer || isInstanceMember);
 
   Field build(SourceLibraryBuilder library) {
     field.name ??= new Name(name, library.target);
     if (type != null) {
@@ skipping 44 matching lines @@
       }
     }
   }
 
   @override
   DartType get builtType => field.type;
 
   @override
   bool get hasImplicitType => type == null;
 }