Regen against latest analyzer

lib/runtime/dart/convert.js

 dart_library.library('dart/convert', null, /* Imports */[
   'dart/_runtime',
   'dart/core',
   'dart/async',
   'dart/typed_data',
   'dart/_internal',
   'dart/collection'
 ], /* Lazy imports */[
 ], function(exports, dart, core, async, typed_data, _internal, collection) {
   'use strict';
@@ skipping 2744 matching lines @@
       this[_parent] = parent;
       super.ListIterable();
     }
     get length() {
       return this[_parent].length;
     }
     elementAt(index) {
       return dart.as(dart.notNull(this[_parent][_isUpgraded]) ? this[_parent].keys[dartx.elementAt](index) : this[_parent][_computeKeys]()[dartx.get](index), core.String);
     }
     get iterator() {
-      return dart.as(dart.notNull(this[_parent][_isUpgraded]) ? this[_parent].keys[dartx.iterator] : this[_parent][_computeKeys]()[dartx.iterator], core.Iterator);
+      return dart.notNull(this[_parent][_isUpgraded]) ? this[_parent].keys[dartx.iterator] : this[_parent][_computeKeys]()[dartx.iterator];
     }
     contains(key) {
       return this[_parent].containsKey(key);
     }
   }
   dart.setSignature(_JsonMapKeyIterable, {
     constructors: () => ({_JsonMapKeyIterable: [_JsonMapKeyIterable, [_JsonMap]]}),
     methods: () => ({elementAt: [core.String, [core.int]]})
   });
   dart.defineExtensionMembers(_JsonMapKeyIterable, ['elementAt', 'contains', 'length', 'iterator']);
@@ skipping 49 matching lines @@
   exports.LineSplitter = LineSplitter;
   exports.StringConversionSink = StringConversionSink;
   exports.ClosableStringSink = ClosableStringSink;
   exports.UNICODE_REPLACEMENT_CHARACTER_RUNE = UNICODE_REPLACEMENT_CHARACTER_RUNE;
   exports.UNICODE_BOM_CHARACTER_RUNE = UNICODE_BOM_CHARACTER_RUNE;
   exports.Utf8Codec = Utf8Codec;
   exports.UTF8 = UTF8;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
 });