Bump to v4.0.0.

internal/isPrototype.js

@@ -0,0 +1,21 @@
+define([], function() {
+
+  /** Used for built-in method references. */
+  var objectProto = Object.prototype;
+
+  /**
+   * Checks if `value` is likely a prototype object.
+   *
+   * @private
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is a prototype, else `false`.
+   */
+  function isPrototype(value) {
+    var Ctor = value && value.constructor,
+        proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto;
+
+    return value === proto;
+  }
+
+  return isPrototype;
+});