Remove countHolders.

.internal/countHolders.js

@@ -1,21 +0,0 @@
-/**
- * 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) {
-  let length = array.length
-  let result = 0
-
-  while (length--) {
-    if (array[length] === placeholder) {
-      ++result
-    }
-  }
-  return result
-}
-
-export default countHolders