Bump to v4.5.1.

_countHolders.js

@@ -0,0 +1,24 @@
+define([], function() {
+
+  /**
+   * Gets the number of `placeholder` occurrences in `array`.
+   *
+   * @private
+   * @param {Array} array The array to inspect.
+   * @param {*} placeholder The placeholder to search for.
+   * @returns {number} Returns the placeholder count.
+   */
+  function countHolders(array, placeholder) {
+    var length = array.length,
+        result = 0;
+
+    while (length--) {
+      if (array[length] === placeholder) {
+        result++;
+      }
+    }
+    return result;
+  }
+
+  return countHolders;
+});