Handle for-in loops

lib/runtime/dart/_interceptors.js

 var _interceptors;
 (function(exports) {
   'use strict';
   class Interceptor extends core.Object {
     Interceptor() {
     }
     ['=='](other) {
       return core.identical(this, other);
     }
     get hashCode() {
@@ skipping 844 matching lines @@
         return dart.as(this.split(re), core.List$(core.String));
       } else {
         return this[_defaultSplit](pattern);
       }
     }
     [_defaultSplit](pattern) {
       let result = new core.List$(core.String).from([]);
       let start = 0;
       let length = 1;
       for (let match of pattern.allMatches(this)) {
-        let matchStart = dart.as(dart.dload(match, 'start'), core.int);
-        let matchEnd = dart.as(dart.dload(match, 'end'), core.int);
+        let matchStart = match.start;
+        let matchEnd = match.end;
         length = dart.notNull(matchEnd) - dart.notNull(matchStart);
         if (length == 0 && start == matchStart) {
           continue;
         }
         let end = matchStart;
         result.add(this.substring(start, end));
         start = matchEnd;
       }
       if (dart.notNull(start) < dart.notNull(this.length) || dart.notNull(length) > 0) {
         result.add(this.substring(start));
@@ skipping 551 matching lines @@
   exports.findInterceptorForType = findInterceptorForType;
   exports.JSBool = JSBool;
   exports.JSNull = JSNull;
   exports.JSIndexable = JSIndexable;
   exports.JSMutableIndexable = JSMutableIndexable;
   exports.JSObject = JSObject;
   exports.JavaScriptObject = JavaScriptObject;
   exports.PlainJavaScriptObject = PlainJavaScriptObject;
   exports.UnknownJavaScriptObject = UnknownJavaScriptObject;
 })(_interceptors || (_interceptors = {}));