Disable closure wrapping by default

lib/runtime/dart/convert.js

 var convert;
 (function(exports) {
   'use strict';
   let ASCII = new AsciiCodec();
   let _ASCII_MASK = 127;
   let _allowInvalid = Symbol('_allowInvalid');
   let _nameToEncoding = Symbol('_nameToEncoding');
   let Codec$ = dart.generic(function(S, T) {
     class Codec extends core.Object {
       Codec() {
@@ skipping 641 matching lines @@
       if (reviver == null)
         return this.decoder.convert(source);
       return new JsonDecoder(reviver).convert(source);
     }
     encode(value, opts) {
       let toEncodable = opts && 'toEncodable' in opts ? opts.toEncodable : null;
       if (toEncodable == null)
         toEncodable = this[_toEncodable$];
       if (toEncodable == null)
         return this.encoder.convert(value);
-      return new JsonEncoder(dart.closureWrap(toEncodable, "(Object) → Object")).convert(value);
+      return new JsonEncoder(dart.as(toEncodable, dart.throw_("Unimplemented type (Object) → Object"))).convert(value);
     }
     get encoder() {
       if (this[_toEncodable$] == null)
         return new JsonEncoder();
-      return new JsonEncoder(dart.closureWrap(this[_toEncodable$], "(Object) → Object"));
+      return new JsonEncoder(dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (Object) → Object")));
     }
     get decoder() {
       if (this[_reviver] == null)
         return new JsonDecoder();
       return new JsonDecoder(this[_reviver]);
     }
   }
   dart.defineNamedConstructor(JsonCodec, 'withReviver');
   class JsonEncoder extends Converter$(core.Object, core.String) {
     JsonEncoder(toEncodable) {
@@ skipping 333 matching lines @@
         for (let i = 1; dart.notNull(i) < dart.notNull(list.length); i = dart.notNull(i) + 1) {
           this.writeString(',');
           this.writeObject(list.get(i));
         }
       }
       this.writeString(']');
     }
     writeMap(map) {
       this.writeString('{');
       let separator = '"';
-      map.forEach(dart.closureWrap(((key, value) => {
+      map.forEach(dart.as(((key, value) => {
         this.writeString(separator);
         separator = ',"';
         this.writeStringContent(key);
         this.writeString('":');
         this.writeObject(value);
-      }).bind(this), "(String, Object) → void"));
+      }).bind(this), dart.throw_("Unimplemented type (String, Object) → void")));
       this.writeString('}');
     }
   }
   _JsonStringifier.BACKSPACE = 8;
   _JsonStringifier.TAB = 9;
   _JsonStringifier.NEWLINE = 10;
   _JsonStringifier.CARRIAGE_RETURN = 13;
   _JsonStringifier.FORM_FEED = 12;
   _JsonStringifier.QUOTE = 34;
   _JsonStringifier.CHAR_0 = 48;
@@ skipping 1331 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.UTF8 = UTF8;
   exports.Utf8Codec = Utf8Codec;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
 })(convert || (convert = {}));