Clarify this is for IE.

Author: kevinpschaaf

test/unit/dom-repeat.html

@@ -3648,7 +3648,7 @@ <h4>x-repeat-chunked</h4>
 
     suite('chunked rendering', function() {
 
-      // Patch requestAnimationFrame to setTimeout to reduce flakiness on CI
+      // Patch requestAnimationFrame to setTimeout to reduce IE test flakiness on CI
       var rAF;
       suiteSetup(function() {
         rAF = window.requestAnimationFrame;