Spec update: change path parsing for non-special URLs

[domenic]

Follows whatwg/url#213.

Waiting on tests in web-platform-tests/wpt#4586 to get rebased.

[annevk]

This doesn't really match the proposed standard change.

[annevk]

Patch for that:

diff --git a/scripts/get-latest-platform-tests.js b/scripts/get-latest-platform-tests.js
index f43b2b4..e045632 100644
--- a/scripts/get-latest-platform-tests.js
+++ b/scripts/get-latest-platform-tests.js
@@ -14,7 +14,7 @@ const request = require("request");
 // 1. Go to https://github.com/w3c/web-platform-tests/tree/master/url
 // 2. Press "y" on your keyboard to get a permalink
 // 3. Copy the commit hash
-const commitHash = "825b63235d43b95a12b4a174e3f8243bd990e741";
+const commitHash = "4ea8eae2fd807ffd22e84f3c2f2ca12f798f8206";
 
 const sourceURL = `https://raw.githubusercontent.com/w3c/web-platform-tests/${commitHash}/url/urltestdata.json`;
 const setterSourceURL = `https://raw.githubusercontent.com/w3c/web-platform-tests/${commitHash}/url/setters_tests.json`;
diff --git a/src/url-state-machine.js b/src/url-state-machine.js
index ce46d69..85bad9c 100644
--- a/src/url-state-machine.js
+++ b/src/url-state-machine.js
@@ -706,9 +706,10 @@ URLStateMachine.prototype["parse relative slash"] = function parseRelativeSlash(
   if (isSpecial(this.url) && (c === p("/") || c === p("\\"))) {
     if (c === p("\\")) {
       this.parseError = true;
-    } else if (c === p("/")) {
-      this.state = "special authority ignore slashes";
     }
+    this.state = "special authority ignore slashes";
+  } else if (c === p("/")) {
+    this.state = "authority";
   } else {
     this.url.username = this.base.username;
     this.url.password = this.base.password;