Simplify isType modules.

isNative.js

@@ -11,15 +11,9 @@ const reRegExpChar = /[\\^$.*+?()[\]{}|]/g;
 /** Used to detect host constructors (Safari). */
 const reIsHostCtor = /^\[object .+?Constructor\]$/;
 
-/** Used to resolve the decompiled source of functions. */
-const funcToString = Function.prototype.toString;
-
-/** Used to check objects for own properties. */
-const hasOwnProperty = Object.prototype.hasOwnProperty;
-
 /** Used to detect if a method is native. */
 const reIsNative = RegExp(`^${
-  funcToString.call(hasOwnProperty)
+  Function.prototype.toString.call(Object.prototype.hasOwnProperty)
     .replace(reRegExpChar, '\\$&')
     .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?')
 }$`);