more optimizations for some break/continue cases

lib/utils.js

@@ -166,6 +166,12 @@ function string_template(text, props) {
     });
 };
 
+function remove(array, el) {
+    for (var i = array.length; --i >= 0;) {
+        if (array[i] === el) array.splice(i, 1);
+    }
+};
+
 function mergeSort(array, cmp) {
     if (array.length < 2) return array.slice();
     function merge(a, b) {