fixes #415, correct type for map literals

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 46 matching lines @@
     }
   }
   dart.setSignature(Encoding, {
     constructors: () => ({Encoding: [Encoding, []]}),
     methods: () => ({decodeStream: [async.Future$(core.String), [async.Stream$(core.List$(core.int))]]}),
     statics: () => ({getByName: [Encoding, [core.String]]}),
     names: ['getByName']
   });
   dart.defineLazyProperties(Encoding, {
     get _nameToEncoding() {
-      return dart.map({"iso_8859-1:1987": LATIN1, "iso-ir-100": LATIN1, "iso_8859-1": LATIN1, "iso-8859-1": LATIN1, latin1: LATIN1, l1: LATIN1, ibm819: LATIN1, cp819: LATIN1, csisolatin1: LATIN1, "iso-ir-6": ASCII, "ansi_x3.4-1968": ASCII, "ansi_x3.4-1986": ASCII, "iso_646.irv:1991": ASCII, "iso646-us": ASCII, "us-ascii": ASCII, us: ASCII, ibm367: ASCII, cp367: ASCII, csascii: ASCII, ascii: ASCII, csutf8: UTF8, "utf-8": UTF8});
+      return dart.map({"iso_8859-1:1987": LATIN1, "iso-ir-100": LATIN1, "iso_8859-1": LATIN1, "iso-8859-1": LATIN1, latin1: LATIN1, l1: LATIN1, ibm819: LATIN1, cp819: LATIN1, csisolatin1: LATIN1, "iso-ir-6": ASCII, "ansi_x3.4-1968": ASCII, "ansi_x3.4-1986": ASCII, "iso_646.irv:1991": ASCII, "iso646-us": ASCII, "us-ascii": ASCII, us: ASCII, ibm367: ASCII, cp367: ASCII, csascii: ASCII, ascii: ASCII, csutf8: UTF8, "utf-8": UTF8}, core.String, Encoding);
     },
     set _nameToEncoding(_) {}
   });
   const _allowInvalid = Symbol('_allowInvalid');
   class AsciiCodec extends Encoding {
     AsciiCodec(opts) {
       let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : false;
       this[_allowInvalid] = allowInvalid;
       super.Encoding();
     }
@@ skipping 2734 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;
 });