fixes browser/runtime_test, and a few extension member fixes

lib/runtime/dart/core.js

 var core = dart.defineLibrary(core, {});
 var _js_helper = dart.lazyImport(_js_helper);
 var _internal = dart.lazyImport(_internal);
 var collection = dart.lazyImport(collection);
 var _interceptors = dart.lazyImport(_interceptors);
 var convert = dart.lazyImport(convert);
 (function(exports, _js_helper, _internal, collection, _interceptors, convert) {
   'use strict';
   class Object {
     constructor() {
@@ skipping 54 matching lines @@
   }
   dart.setSignature(_Proxy, {
     constructors: () => ({_Proxy: [_Proxy, []]})
   });
   let proxy = dart.const(new _Proxy());
   class bool extends Object {
     static fromEnvironment(name, opts) {
       let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : false;
       throw new UnsupportedError('bool.fromEnvironment can only be used as a const constructor');
     }
-    toString() {
+    [dart.extensionMember('toString')]() {
       return this ? "true" : "false";
     }
   }
   dart.setSignature(bool, {
     constructors: () => ({fromEnvironment: [bool, [String], {defaultValue: bool}]})
   });
   let Comparator$ = dart.generic(function(T) {
     let Comparator = dart.typedef('Comparator', () => dart.functionType(int, [T, T]));
     return Comparator;
   });
@@ skipping 249 matching lines @@
       return dart.as(_js_helper.Primitives.getSeconds(this), int);
     }
     get millisecond() {
       return dart.as(_js_helper.Primitives.getMilliseconds(this), int);
     }
     get weekday() {
       return dart.as(_js_helper.Primitives.getWeekday(this), int);
     }
   }
   DateTime[dart.implements] = () => [Comparable];
-  dart.defineExtensionMembers(DateTime, ['compareTo']);
   dart.defineNamedConstructor(DateTime, 'utc');
   dart.defineNamedConstructor(DateTime, 'now');
   dart.defineNamedConstructor(DateTime, 'fromMillisecondsSinceEpoch');
   dart.defineNamedConstructor(DateTime, '_internal');
   dart.defineNamedConstructor(DateTime, '_now');
   dart.setSignature(DateTime, {
     constructors: () => ({
       DateTime: [DateTime, [int], [int, int, int, int, int, int]],
       utc: [DateTime, [int], [int, int, int, int, int, int]],
       now: [DateTime, []],
@@ skipping 16 matching lines @@
     statics: () => ({
       parse: [DateTime, [String]],
       _fourDigits: [String, [int]],
       _sixDigits: [String, [int]],
       _threeDigits: [String, [int]],
       _twoDigits: [String, [int]],
       _brokenDownDateToMillisecondsSinceEpoch: [int, [int, int, int, int, int, int, int, bool]]
     }),
     names: ['parse', '_fourDigits', '_sixDigits', '_threeDigits', '_twoDigits', '_brokenDownDateToMillisecondsSinceEpoch']
   });
+  dart.defineExtensionMembers(DateTime, ['compareTo']);
   DateTime.MONDAY = 1;
   DateTime.TUESDAY = 2;
   DateTime.WEDNESDAY = 3;
   DateTime.THURSDAY = 4;
   DateTime.FRIDAY = 5;
   DateTime.SATURDAY = 6;
   DateTime.SUNDAY = 7;
   DateTime.DAYS_PER_WEEK = 7;
   DateTime.JANUARY = 1;
   DateTime.FEBRUARY = 2;
@@ skipping 162 matching lines @@
       return dart.notNull(this[_duration]) < 0;
     }
     abs() {
       return new Duration._microseconds(this[_duration][dartx.abs]());
     }
     ['unary-']() {
       return new Duration._microseconds(-dart.notNull(this[_duration]));
     }
   }
   Duration[dart.implements] = () => [Comparable$(Duration)];
-  dart.defineExtensionMembers(Duration, ['compareTo']);
   dart.defineNamedConstructor(Duration, '_microseconds');
   dart.setSignature(Duration, {
     constructors: () => ({
       Duration: [Duration, [], {days: int, hours: int, minutes: int, seconds: int, milliseconds: int, microseconds: int}],
       _microseconds: [Duration, [int]]
     }),
     methods: () => ({
       '+': [Duration, [Duration]],
       '-': [Duration, [Duration]],
       '*': [Duration, [num]],
       '~/': [Duration, [int]],
       '<': [bool, [Duration]],
       '>': [bool, [Duration]],
       '<=': [bool, [Duration]],
       '>=': [bool, [Duration]],
       compareTo: [int, [Duration]],
       abs: [Duration, []],
       'unary-': [Duration, []]
     })
   });
+  dart.defineExtensionMembers(Duration, ['compareTo']);
   Duration.MICROSECONDS_PER_MILLISECOND = 1000;
   Duration.MILLISECONDS_PER_SECOND = 1000;
   Duration.SECONDS_PER_MINUTE = 60;
   Duration.MINUTES_PER_HOUR = 60;
   Duration.HOURS_PER_DAY = 24;
   Duration.MICROSECONDS_PER_SECOND = dart.notNull(Duration.MICROSECONDS_PER_MILLISECOND) * dart.notNull(Duration.MILLISECONDS_PER_SECOND);
   Duration.MICROSECONDS_PER_MINUTE = dart.notNull(Duration.MICROSECONDS_PER_SECOND) * dart.notNull(Duration.SECONDS_PER_MINUTE);
   Duration.MICROSECONDS_PER_HOUR = dart.notNull(Duration.MICROSECONDS_PER_MINUTE) * dart.notNull(Duration.MINUTES_PER_HOUR);
   Duration.MICROSECONDS_PER_DAY = dart.notNull(Duration.MICROSECONDS_PER_HOUR) * dart.notNull(Duration.HOURS_PER_DAY);
   Duration.MILLISECONDS_PER_MINUTE = dart.notNull(Duration.MILLISECONDS_PER_SECOND) * dart.notNull(Duration.SECONDS_PER_MINUTE);
@@ skipping 664 matching lines @@
       static generate(count, generator) {
         if (generator === void 0)
           generator = null;
         if (dart.notNull(count) <= 0)
           return new (_internal.EmptyIterable$(E))();
         return new (exports._GeneratorIterable$(E))(count, generator);
       }
       [dart.JsSymbol.iterator]() {
         return new dart.JsIterator(this[dartx.iterator]);
       }
-      join(separator) {
+      [dart.extensionMember('join')](separator) {
         if (separator === void 0)
           separator = "";
         let buffer = new StringBuffer();
         buffer.writeAll(this, separator);
         return dart.toString(buffer);
       }
     }
     dart.setSignature(Iterable, {
       constructors: () => ({
         Iterable: [Iterable$(E), []],
         generate: [Iterable$(E), [int], [dart.functionType(E, [int])]]
       }),
-      methods: () => ({join: [String, [], [String]]})
+      methods: () => ({[dartx.join]: [String, [], [String]]})
     });
     return Iterable;
   });
   let Iterable = Iterable$();
   let _Generator$ = dart.generic(function(E) {
     let _Generator = dart.typedef('_Generator', () => dart.functionType(E, [int]));
     return _Generator;
   });
   let _Generator = _Generator$();
   let _end = dart.JsSymbol('_end');
@@ skipping 35 matching lines @@
         let newEnd = dart.notNull(this[_start]) + dart.notNull(count);
         if (dart.notNull(newEnd) >= dart.notNull(this[_end]))
           return this;
         return new (exports._GeneratorIterable$(E)).slice(this[_start], newEnd, this[_generator]);
       }
       static _id(n) {
         return n;
       }
     }
     _GeneratorIterable[dart.implements] = () => [_internal.EfficientLength];
-    dart.defineExtensionMembers(_GeneratorIterable, ['skip', 'take', 'iterator', 'length']);
     dart.defineNamedConstructor(_GeneratorIterable, 'slice');
     dart.setSignature(_GeneratorIterable, {
       constructors: () => ({
         _GeneratorIterable: [exports._GeneratorIterable$(E), [int, dart.functionType(E, [int])]],
         slice: [exports._GeneratorIterable$(E), [int, int, _Generator$(E)]]
       }),
       methods: () => ({
         skip: [Iterable$(E), [int]],
         take: [Iterable$(E), [int]]
       }),
       statics: () => ({_id: [int, [int]]}),
       names: ['_id']
     });
+    dart.defineExtensionMembers(_GeneratorIterable, ['skip', 'take', 'iterator', 'length']);
     return _GeneratorIterable;
   });
   dart.defineLazyClassGeneric(exports, '_GeneratorIterable', {get: _GeneratorIterable$});
   let _index = dart.JsSymbol('_index');
   let _current = dart.JsSymbol('_current');
   let _GeneratorIterator$ = dart.generic(function(E) {
     class _GeneratorIterator extends Object {
       _GeneratorIterator(index, end, generator) {
         this[_index] = index;
         this[_end] = end;
@@ skipping 353 matching lines @@
             if (_isLeadSurrogate(previousCode)) {
               return _combineSurrogatePair(previousCode, code);
             }
           }
           return code;
         }
       }
       dart.setSignature(Runes, {
         constructors: () => ({Runes: [exports.Runes, [String]]})
       });
+      dart.defineExtensionMembers(Runes, ['iterator', 'last']);
       return Runes;
     }
   });
   function _isLeadSurrogate(code) {
     return (dart.notNull(code) & 64512) == 55296;
   }
   dart.fn(_isLeadSurrogate, bool, [int]);
   function _isTrailSurrogate(code) {
     return (dart.notNull(code) & 64512) == 56320;
   }
@@ skipping 1621 matching lines @@
   exports.StackTrace = StackTrace;
   exports.Stopwatch = Stopwatch;
   exports.String = String;
   exports.RuneIterator = RuneIterator;
   exports.StringBuffer = StringBuffer;
   exports.StringSink = StringSink;
   exports.Symbol = Symbol;
   exports.Type = Type;
   exports.Uri = Uri;
 })(core, _js_helper, _internal, collection, _interceptors, convert);