Address code-review comments for https://codereview.chromium.org//11553015

sdk/lib/_internal/compiler/implementation/lib/native_helper.dart

Index: sdk/lib/_internal/compiler/implementation/lib/native_helper.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/native_helper.dart b/sdk/lib/_internal/compiler/implementation/lib/native_helper.dart
index 353652d9bc9c04686ed56f67097bd78ebe5c51af..f6f88c707939baaa596e9ce63a6a97ac97a48517 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/native_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/native_helper.dart
@@ -236,9 +236,9 @@ dynamicBind(var obj,
 
   var method = dynamicBindLookup(hasOwnPropertyFunction, tag, methods);
   if (method == null) {
-    String altTag = alternateTag(obj, tag);
-    if (altTag != null) {
-      method = dynamicBindLookup(hasOwnPropertyFunction, altTag, methods);
+    String secondTag = alternateTag(obj, tag);
+    if (secondTag != null) {
+      method = dynamicBindLookup(hasOwnPropertyFunction, secondTag, methods);
     }
   }