Bump to v4.0.0.

internal/createPartialWrapper.js

@@ -1,3 +1,4 @@
+import apply from './apply';
 import createCtorWrapper from './createCtorWrapper';
 import root from './root';
 
@@ -5,29 +6,28 @@ import root from './root';
 var BIND_FLAG = 1;
 
 /**
- * Creates a function that wraps `func` and invokes it with the optional `this`
+ * Creates a function that wraps `func` to invoke it with the optional `this`
  * binding of `thisArg` and the `partials` prepended to those provided to
  * the wrapper.
  *
  * @private
- * @param {Function} func The function to partially apply arguments to.
- * @param {number} bitmask The bitmask of flags. See `createWrapper` for more details.
+ * @param {Function} func The function to wrap.
+ * @param {number} bitmask The bitmask of wrapper flags. See `createWrapper` for more details.
  * @param {*} thisArg The `this` binding of `func`.
  * @param {Array} partials The arguments to prepend to those provided to the new function.
- * @returns {Function} Returns the new bound function.
+ * @returns {Function} Returns the new wrapped function.
  */
 function createPartialWrapper(func, bitmask, thisArg, partials) {
   var isBind = bitmask & BIND_FLAG,
       Ctor = createCtorWrapper(func);
 
   function wrapper() {
-    // Avoid `arguments` object use disqualifying optimizations by
-    // converting it to an array before providing it `func`.
     var argsIndex = -1,
         argsLength = arguments.length,
         leftIndex = -1,
         leftLength = partials.length,
-        args = Array(leftLength + argsLength);
+        args = Array(leftLength + argsLength),
+        fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
 
     while (++leftIndex < leftLength) {
       args[leftIndex] = partials[leftIndex];
@@ -35,8 +35,7 @@ function createPartialWrapper(func, bitmask, thisArg, partials) {
     while (argsLength--) {
       args[leftIndex++] = arguments[++argsIndex];
     }
-    var fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
-    return fn.apply(isBind ? thisArg : this, args);
+    return apply(fn, isBind ? thisArg : this, args);
   }
   return wrapper;
 }