fixes private named constructors

lib/runtime/dart/_js_helper.js

 var _js_helper;
 (function(exports) {
   'use strict';
   class NoSideEffects extends core.Object {
     NoSideEffects() {
     }
   }
   class NoThrows extends core.Object {
     NoThrows() {
     }
   }
   class NoInline extends core.Object {
     NoInline() {
     }
   }
   class IrRepresentation extends core.Object {
     IrRepresentation(value) {
       this.value = value;
     }
   }
   class Native extends core.Object {
     Native(name) {
       this.name = name;
     }
   }
+  let _$ = Symbol('_');
   let _throwUnmodifiable = Symbol('_throwUnmodifiable');
-  let _$ = Symbol('_');
   let ConstantMap$ = dart.generic(function(K, V) {
     class ConstantMap extends core.Object {
-      ConstantMap$_() {
+      [_$]() {
       }
       get isEmpty() {
         return this.length === 0;
       }
       get isNotEmpty() {
         return !dart.notNull(this.isEmpty);
       }
       toString() {
         return collection.Maps.mapToString(this);
       }
@@ skipping 18 matching lines @@
     }
     dart.defineNamedConstructor(ConstantMap, _$);
     return ConstantMap;
   });
   let ConstantMap = ConstantMap$(dart.dynamic, dart.dynamic);
   let _jsObject = Symbol('_jsObject');
   let _keys = Symbol('_keys');
   let _fetch = Symbol('_fetch');
   let ConstantStringMap$ = dart.generic(function(K, V) {
     class ConstantStringMap extends ConstantMap$(K, V) {
-      ConstantStringMap$_(length, jsObject$, keys$) {
+      [_$](length, jsObject$, keys$) {
         this.length = length;
         this[_jsObject] = jsObject$;
         this[_keys] = keys$;
-        super.ConstantMap$_();
+        super[_$]();
       }
       containsValue(needle) {
         return this.values.any((value) => dart.equals(value, needle));
       }
       containsKey(key) {
         if (!(typeof key == 'string'))
           return false;
         if (dart.equals('__proto__', key))
           return false;
         return jsHasOwnProperty(this[_jsObject], dart.as(key, core.String));
@@ skipping 20 matching lines @@
         return new _internal.MappedIterable(this[_keys], dart.closureWrap(((key) => this[_fetch](key)).bind(this), "(K) → V"));
       }
     }
     dart.defineNamedConstructor(ConstantStringMap, _$);
     return ConstantStringMap;
   });
   let ConstantStringMap = ConstantStringMap$(dart.dynamic, dart.dynamic);
   let _protoValue = Symbol('_protoValue');
   let ConstantProtoMap$ = dart.generic(function(K, V) {
     class ConstantProtoMap extends ConstantStringMap$(K, V) {
-      ConstantProtoMap$_(length, jsObject, keys, protoValue) {
+      [_$](length, jsObject, keys, protoValue) {
         this[_protoValue] = protoValue;
-        super.ConstantStringMap$_(dart.as(length, core.int), jsObject, dart.as(keys, core.List$(K)));
+        super[_$](dart.as(length, core.int), jsObject, dart.as(keys, core.List$(K)));
       }
       containsKey(key) {
         if (!(typeof key == 'string'))
           return false;
         if (dart.equals('__proto__', key))
           return true;
         return jsHasOwnProperty(this[_jsObject], dart.as(key, core.String));
       }
       [_fetch](key) {
         return dart.equals('__proto__', key) ? this[_protoValue] : jsPropertyAccess(this[_jsObject], dart.as(key, core.String));
@@ skipping 19 matching lines @@
     }
     return _ConstantMapKeyIterable;
   });
   let _ConstantMapKeyIterable = _ConstantMapKeyIterable$(dart.dynamic);
   let _jsData = Symbol('_jsData');
   let _getMap = Symbol('_getMap');
   let GeneralConstantMap$ = dart.generic(function(K, V) {
     class GeneralConstantMap extends ConstantMap$(K, V) {
       GeneralConstantMap(jsData) {
         this[_jsData] = jsData;
-        super.ConstantMap$_();
+        super[_$]();
       }
       [_getMap]() {
         if (!this.$map) {
           let backingMap = new collection.LinkedHashMap();
           this.$map = fillLiteralMap(this[_jsData], backingMap);
         }
         return this.$map;
       }
       containsValue(needle) {
         return this[_getMap]().containsValue(needle);
@@ skipping 1424 matching lines @@
     }
     get isGetterStub() {
       return false;
     }
     invokeOn(victim, invocation) {
       let receiver = this.interceptor === null ? victim : this.interceptor;
       return dart.dinvoke(receiver, 'noSuchMethod', invocation);
     }
   }
   class ReflectionInfo extends core.Object {
-    ReflectionInfo$internal(jsFunction, data, isAccessor, requiredParameterCount, optionalParameterCount, areOptionalParametersNamed, functionType) {
+    internal(jsFunction, data, isAccessor, requiredParameterCount, optionalParameterCount, areOptionalParametersNamed, functionType) {
       this.jsFunction = jsFunction;
       this.data = data;
       this.isAccessor = isAccessor;
       this.requiredParameterCount = requiredParameterCount;
       this.optionalParameterCount = optionalParameterCount;
       this.areOptionalParametersNamed = areOptionalParametersNamed;
       this.functionType = functionType;
       this.cachedSortedIndices = null;
     }
     ReflectionInfo(jsFunction) {
@@ skipping 1561 matching lines @@
       class JavaScriptIndexingBehavior extends _interceptors.JSMutableIndexable {
       }
       return JavaScriptIndexingBehavior;
     }
   });
   class TypeErrorImplementation extends core.Error {
     TypeErrorImplementation(value, type) {
       this.message = `type '${Primitives.objectTypeName(value)}' is not a subtype ` + `of type '${type}'`;
       super.Error();
     }
-    TypeErrorImplementation$fromMessage(message) {
+    fromMessage(message) {
       this.message = message;
       super.Error();
     }
     toString() {
       return this.message;
     }
   }
   dart.defineNamedConstructor(TypeErrorImplementation, 'fromMessage');
   class CastErrorImplementation extends core.Error {
     CastErrorImplementation(actualType, expectedType) {
@@ skipping 791 matching lines @@
   exports.UnimplementedNoSuchMethodError = UnimplementedNoSuchMethodError;
   exports.random64 = random64;
   exports.jsonEncodeNative = jsonEncodeNative;
   exports.getIsolateAffinityTag = getIsolateAffinityTag;
   exports.loadDeferredLibrary = loadDeferredLibrary;
   exports.MainError = MainError;
   exports.missingMain = missingMain;
   exports.badMain = badMain;
   exports.mainHasTooManyParameters = mainHasTooManyParameters;
 })(_js_helper || (_js_helper = {}));