fix corner case in ie8 (#3216)

fixes #3215

lib/utils.js

@@ -172,9 +172,8 @@ function string_template(text, props) {
 }
 
 function remove(array, el) {
-    for (var i = array.length; --i >= 0;) {
-        if (array[i] === el) array.splice(i, 1);
-    }
+    var index = array.indexOf(el);
+    if (index >= 0) array.splice(index, 1);
 }
 
 function makePredicate(words) {