fixes #427, static fields emitted outside the scope of their class

test/codegen/expect/collection/src/canonicalized_map.js

 dart_library.library('collection/src/canonicalized_map', null, /* Imports */[
   'dart/_runtime',
   'dart/core',
   'collection/src/utils',
   'dart/collection'
 ], /* Lazy imports */[
 ], function(exports, dart, core, utils, collection) {
   'use strict';
   let dartx = dart.dartx;
   const _base = Symbol('_base');
@@ skipping 44 matching lines @@
         dart.as(f, dart.functionType(dart.void, [K, V]));
         this[_base].forEach(dart.fn((key, pair) => f(pair.first, pair.last), dart.void, [C, utils.Pair$(K, V)]));
       }
       get isEmpty() {
         return this[_base].isEmpty;
       }
       get isNotEmpty() {
         return this[_base].isNotEmpty;
       }
       get keys() {
-        return dart.as(this[_base].values[dartx.map](dart.fn(pair => pair.first, K, [utils.Pair$(K, V)])), core.Iterable$(K));
+        return this[_base].values[dartx.map](dart.fn(pair => pair.first, K, [utils.Pair$(K, V)]));
       }
       get length() {
         return this[_base].length;
       }
       putIfAbsent(key, ifAbsent) {
         dart.as(key, K);
         dart.as(ifAbsent, dart.functionType(V, []));
         return this[_base].putIfAbsent(dart.as(dart.dcall(this[_canonicalize], key), C), dart.fn(() => new (utils.Pair$(K, V))(key, ifAbsent()), utils.Pair$(K, V), [])).last;
       }
       remove(key) {
         if (!dart.notNull(this[_isValidKey](key))) return null;
         let pair = this[_base].remove(dart.dcall(this[_canonicalize], key));
         return pair == null ? null : pair.last;
       }
       get values() {
-        return dart.as(this[_base].values[dartx.map](dart.fn(pair => pair.last, V, [utils.Pair$(K, V)])), core.Iterable$(V));
+        return this[_base].values[dartx.map](dart.fn(pair => pair.last, V, [utils.Pair$(K, V)]));
       }
       toString() {
         return collection.Maps.mapToString(this);
       }
       [_isValidKey](key) {
         return (key == null || dart.is(key, K)) && (this[_isValidKeyFn] == null || dart.notNull(dart.as(dart.dcall(this[_isValidKeyFn], key), core.bool)));
       }
     }
     CanonicalizedMap[dart.implements] = () => [core.Map$(K, V)];
     dart.defineNamedConstructor(CanonicalizedMap, 'from');
@@ skipping 15 matching lines @@
         [_isValidKey]: [core.bool, [core.Object]]
       })
     });
     return CanonicalizedMap;
   });
   let CanonicalizedMap = CanonicalizedMap$();
   // Exports:
   exports.CanonicalizedMap$ = CanonicalizedMap$;
   exports.CanonicalizedMap = CanonicalizedMap;
 });