fix analyzer failing to resolve loop variable nodes

pkg/dev_compiler/lib/js/common/dart_sdk.js

Index: pkg/dev_compiler/lib/js/common/dart_sdk.js
diff --git a/pkg/dev_compiler/lib/js/common/dart_sdk.js b/pkg/dev_compiler/lib/js/common/dart_sdk.js
index 9e510b10195c35269d28327630d402f14d3f4ad1..439a3cf22182b04339e63abb791d5c7ccb7d281a 100644
--- a/pkg/dev_compiler/lib/js/common/dart_sdk.js
+++ b/pkg/dev_compiler/lib/js/common/dart_sdk.js
@@ -3335,7 +3335,7 @@
         protoChain[dartx.add](current);
         current = _debugger.safeGetProperty(current, '__proto__');
       }
-      for (/* Unimplemented unknown name */current of protoChain) {
+      for (current of protoChain) {
         for (let symbol of _debugger.getOwnPropertySymbols(current)) {
           let dartName = _debugger.symbolName(symbol);
           if (dart.test(_debugger.hasMethod(object, dartName))) {
@@ -3351,7 +3351,7 @@
           properties.add(new _debugger.NameValuePair({name: dartName, value: value}));
         }
       }
-      for (/* Unimplemented unknown name */current of protoChain) {
+      for (current of protoChain) {
         let className = dart.dload(dart.getReifiedType(current), 'name');
         for (let name of _debugger.getOwnPropertyNames(current)) {
           if (dart.test(_debugger.ObjectFormatter._customNames.contains(name)) || dart.equals(name, className)) continue;