Fix hints reported by analyzer.

pkg/compiler/lib/src/dart2js.dart

 // Copyright (c) 2013, 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 dart2js.cmdline;
 
 import 'dart:async' show EventSink, Future;
 import 'dart:convert' show UTF8, LineSplitter;
 import 'dart:io' show exit, File, FileMode, Platform, stdin, stderr;
 
@@ skipping 104 matching lines @@
   List<String> options = new List<String>();
   List<String> explicitOutputArguments = <String>[];
   bool wantHelp = false;
   bool wantVersion = false;
   bool analyzeOnly = false;
   bool analyzeAll = false;
   bool resolveOnly = false;
   Uri resolutionOutput = currentDirectory.resolve('out.data');
   bool allowNativeExtensions = false;
   bool trustTypeAnnotations = false;
-  bool trustJSInteropTypeAnnotations = false;
   bool checkedMode = false;
   List<String> hints = <String>[];
   bool verbose;
   bool throwOnError;
   int throwOnErrorCount;
   bool showWarnings;
   bool showHints;
   bool enableColors;
   // List of provided options that imply that output is expected.
   List<String> optionsImplyCompilation = <String>[];
@@ skipping 100 matching lines @@
     verbose = true;
     passThrough('--verbose');
   }
 
   void setTrustTypeAnnotations(String argument) {
     trustTypeAnnotations = true;
     implyCompilation(argument);
   }
 
   void setTrustJSInteropTypeAnnotations(String argument) {
-    trustJSInteropTypeAnnotations = true;
     implyCompilation(argument);
   }
 
   void setTrustPrimitives(String argument) {
     implyCompilation(argument);
   }
 
   void setCheckedMode(String argument) {
     checkedMode = true;
     passThrough(argument);
@@ skipping 776 matching lines @@
   @override
   void close() {
     // Do nothing.
   }
 
   @override
   void addError(errorEvent, [StackTrace stackTrace]) {
     // Ignore
   }
 }