fix(urlUtils): make IPv6 URL's hostname wrapped in square brackets in IE/Edge

IE 9-11 and Edge 16-17 (fixed in 18 Preview) incorrectly don't wrap IPv6
addresses' hostnames in square brackets when parsed out of an anchor element.

Fixes #16692
Closes #16715

Author: mgol

src/ng/urlUtils.js

@@ -10,6 +10,12 @@ var urlParsingNode = window.document.createElement('a');
 var originUrl = urlResolve(window.location.href);
 var baseUrlParsingNode;
 
+urlParsingNode.href = 'http://[::1]';
+
+// Support: IE 9-11 only, Edge 16-17 only (fixed in 18 Preview)
+// IE/Edge don't wrap IPv6 addresses' hostnames in square brackets
+// when parsed out of an anchor element.
+var ipv6InBrackets = urlParsingNode.hostname === '[::1]';
 
 /**
  *
@@ -72,13 +78,19 @@ function urlResolve(url) {
 
   urlParsingNode.setAttribute('href', href);
 
+  var hostname = urlParsingNode.hostname;
+
+  if (!ipv6InBrackets && hostname.indexOf(':') > -1) {
+    hostname = '[' + hostname + ']';
+  }
+
   return {
     href: urlParsingNode.href,
     protocol: urlParsingNode.protocol ? urlParsingNode.protocol.replace(/:$/, '') : '',
     host: urlParsingNode.host,
     search: urlParsingNode.search ? urlParsingNode.search.replace(/^\?/, '') : '',
     hash: urlParsingNode.hash ? urlParsingNode.hash.replace(/^#/, '') : '',
-    hostname: urlParsingNode.hostname,
+    hostname: hostname,
     port: urlParsingNode.port,
     pathname: (urlParsingNode.pathname.charAt(0) === '/')
       ? urlParsingNode.pathname

test/ng/urlUtilsSpec.js

@@ -31,6 +31,19 @@ describe('urlUtils', function() {
       var parsed = urlResolve('/');
       expect(parsed.pathname).toBe('/');
     });
+
+    it('should return an IPv6 hostname wrapped in brackets', function() {
+      // Support: IE 9-11 only, Edge 16-17 only (fixed in 18 Preview)
+      // IE/Edge don't wrap IPv6 addresses' hostnames in square brackets
+      // when parsed out of an anchor element.
+      var parsed = urlResolve('http://[::1]/');
+      expect(parsed.hostname).toBe('[::1]');
+    });
+
+    it('should not put the domain in brackets for the hostname field', function() {
+      var parsed = urlResolve('https://google.com/');
+      expect(parsed.hostname).toBe('google.com');
+    });
   });