diff --git a/src/_legacy.js b/src/_legacy.js
index <HASH>..<HASH> 100644
--- a/src/_legacy.js
+++ b/src/_legacy.js
@@ -16,20 +16,6 @@
 		};
 	}
 
-	if ( !Element.prototype.contains ) {
-		Element.prototype.contains = function ( el ) {
-			while ( el.parentNode ) {
-				if ( el.parentNode === this ) {
-					return true;
-				}
-
-				el = el.parentNode;
-			}
-
-			return false;
-		};
-	}
-
 	if ( !String.prototype.trim ) {
 		String.prototype.trim = function () {
 			return this.replace(/^\s+/, '').replace(/\s+$/, '');
removed newly redundant element.contains shim