Bump to v4.5.1.

_getPlaceholder.js

@@ -0,0 +1,16 @@
+define([], function() {
+
+  /**
+   * Gets the argument placeholder value for `func`.
+   *
+   * @private
+   * @param {Function} func The function to inspect.
+   * @returns {*} Returns the placeholder value.
+   */
+  function getPlaceholder(func) {
+    var object = func;
+    return object.placeholder;
+  }
+
+  return getPlaceholder;
+});