Add URL.canParse to externs.

https://url.spec.whatwg.org/#dom-url-canparse

PiperOrigin-RevId: 618998846

Author: Closure Team

externs/browser/url.js

@@ -186,6 +186,14 @@ URL.domainToUnicode = function(domain) {};
  */
 URL.createObjectURL = function(obj) {};
 
+/**
+ * @see https://url.spec.whatwg.org
+ * @param {!URL|string} url
+ * @param {(!URL|string)=} base
+ * @return {boolean}
+ */
+URL.canParse = function(url, base) {};
+
 /**
  * @see http://www.w3.org/TR/FileAPI/#dfn-revokeObjectURL
  * @param {!URL|string} url