remove another old analyzer workaround

lib/runtime/dart/core.js

 var core;
 (function(exports) {
   'use strict';
   class Object {
     constructor() {
       let name = this.constructor.name;
       let init = this[name];
       let result = void 0;
       if (init)
         result = init.apply(this, arguments);
@@ skipping 1123 matching lines @@
   let _generator = dart.JsSymbol('_generator');
   let _id = dart.JsSymbol('_id');
   let $iterator = dart.JsSymbol('$iterator');
   let $skip = dart.JsSymbol('$skip');
   let $take = dart.JsSymbol('$take');
   let _GeneratorIterable$ = dart.generic(function(E) {
     class _GeneratorIterable extends collection.IterableBase$(E) {
       _GeneratorIterable(end, generator) {
         this[_end] = end;
         this[_start] = 0;
-        this[_generator] = dart.as(generator != null ? generator : _GeneratorIterable[_id], _Generator);
+        this[_generator] = dart.as(generator != null ? generator : _GeneratorIterable[_id], _Generator$(E));
         super.IterableBase();
       }
       slice(start, end, generator) {
         this[_start] = start;
         this[_end] = end;
         this[_generator] = generator;
         super.IterableBase();
       }
       get [exports.$iterator]() {
         return new (_GeneratorIterator$(E))(this[_start], this[_end], this[_generator]);
@@ skipping 1990 matching lines @@
   exports.Symbol = Symbol;
   exports.Type = Type;
   exports.$forEach = $forEach;
   exports.$map = $map;
   exports.$toList = $toList;
   exports.$isEmpty = $isEmpty;
   exports.$removeLast = $removeLast;
   exports.$fold = $fold;
   exports.Uri = Uri;
 })(core || (core = {}));