Revert "Add an interface for request parameters"

pkg/analyzer_plugin/tool/spec/codegen_dart_protocol.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 file.
 
 import 'dart:convert';
 
 import 'package:analyzer/src/codegen/tools.dart';
 import 'package:html/dom.dart' as dom;
 
 import 'api.dart';
@@ skipping 205 matching lines @@
       });
       toHtmlVisitor.p(() {
         toHtmlVisitor.write(disclaimer);
       });
     }));
     write('class $className');
     if (impliedType.kind == 'refactoringFeedback') {
       writeln(' extends RefactoringFeedback implements HasToJson {');
     } else if (impliedType.kind == 'refactoringOptions') {
       writeln(' extends RefactoringOptions implements HasToJson {');
-    } else if (impliedType.kind == 'requestParams') {
-      writeln(' implements RequestParams {');
     } else if (impliedType.kind == 'requestResult') {
       writeln(' implements ResponseResult {');
     } else {
       writeln(' {');
     }
     indent(() {
       if (impliedType.kind == 'requestResult') {
         emitEmptyToJsonMember();
         writeln();
       }
@@ skipping 162 matching lines @@
       }
       toHtmlVisitor.p(() {
         toHtmlVisitor.write(disclaimer);
       });
     }));
     write('class $className');
     if (impliedType.kind == 'refactoringFeedback') {
       writeln(' extends RefactoringFeedback {');
     } else if (impliedType.kind == 'refactoringOptions') {
       writeln(' extends RefactoringOptions {');
-    } else if (impliedType.kind == 'requestParams') {
-      writeln(' implements RequestParams {');
     } else if (impliedType.kind == 'requestResult') {
       writeln(' implements ResponseResult {');
     } else {
       writeln(' implements HasToJson {');
     }
     indent(() {
       if (emitSpecialStaticMembers(className)) {
         writeln();
       }
       for (TypeObjectField field in type.fields) {
@@ skipping 849 matching lines @@
 
   @override
   String get asClosure => '($type value) => ${callback('value')}';
 
   @override
   bool get isIdentity => false;
 
   @override
   String asSnippet(String value) => callback(value);
 }