Correct processing of non-string members of a base URL record

Some of these values may be null (or in the case of port, an integer) and
must be converted to strings before they can be applied to URLPatternInit.

The conversion of the port to an integer is also necessary in the encoding
callbacks.

Addresses #202, at least in part.

spec.bs

@@ -18,6 +18,9 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
   type: dfn
     text: IdentifierPart; url: #prod-IdentifierPart
     text: IdentifierStart; url: #prod-IdentifierStart
+spec: URL; urlPrefix: https://url.spec.whatwg.org/
+  type: dfn
+    text: serialize an integer; url: #serialize-an-integer
 </pre>
 
 <h2 id=urlpattern-class>The {{URLPattern}} class</h2>
@@ -1737,7 +1740,7 @@ To <dfn>convert a modifier to a string</dfn> given a [=part/modifier=] |modifier
      <p class="note">Note, we set the [=URL record=]'s [=url/scheme=] in order for the [=basic URL parser=] to recognize and normalize default port values.</p>
   1. Let |parseResult| be the result of running [=basic URL parser=] given |portValue| with |dummyURL| as <i>[=basic URL parser/url=]</i> and [=port state=] as <i>[=basic URL parser/state override=]</i>.
   1. If |parseResult| is failure, then throw a {{TypeError}}.
-  1. Return |dummyURL|'s [=url/port=] or empty string if it is null.
+  1. Return |dummyURL|'s [=url/port=], [=serialize an integer|serialized=], or empty string if it is null.
 </div>
 
 <div algorithm>
@@ -1823,11 +1826,22 @@ To <dfn>convert a modifier to a string</dfn> given a [=part/modifier=] |modifier
     1. If |init|["{{URLPatternInit/protocol}}"] does not [=map/exist=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/scheme=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}" and "{{URLPatternInit/username}}", then set |result|["{{URLPatternInit/username}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/username=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/username}}" and "{{URLPatternInit/password}}", then set |result|["{{URLPatternInit/password}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/password=] and |type|.
-    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/host=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then set |result|["{{URLPatternInit/port}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/port=] and |type|.
+    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then:
+      1. Let |baseHost| be |baseURL|'s [=url/host=].
+      1. If |baseHost| is null, then set |baseHost| to the empty string.
+      1. Set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseHost| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then:
+      1. If |baseURL|'s [=url/port=] is null, then set |result|["{{URLPatternInit/port}}"] to the empty string.
+      1. Otherwise, set |result|["{{URLPatternInit/port}}"] to |baseURL|'s [=url/port=], [=serialize an integer|serialized=].
     1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", and "{{URLPatternInit/pathname}}", then set |result|["{{URLPatternInit/pathname}}"] to the result of [=processing a base URL string=] given the result of [=URL path serializing=] |baseURL| and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/query=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/fragment=] and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then:
+      1. Let |baseQuery| be |baseURL|'s [=url/query=].
+      1. If |baseQuery| is null, then set |baseQuery| to the empty string.
+      1. Set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseQuery| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then:
+      1. Let |baseFragment| be |baseURL|'s [=url/fragment=].
+      1. If |baseFragment| is null, then set |baseFragment| to the empty string.
+      1. Set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseFragment| and |type|.
   1. If |init|["{{URLPatternInit/protocol}}"] [=map/exists=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=process protocol for init=] given |init|["{{URLPatternInit/protocol}}"] and |type|.
   1. If |init|["{{URLPatternInit/username}}"] [=map/exists=], then set |result|["{{URLPatternInit/username}}"] to the result of [=process username for init=] given |init|["{{URLPatternInit/username}}"] and |type|.
   1. If |init|["{{URLPatternInit/password}}"] [=map/exists=], then set |result|["{{URLPatternInit/password}}"] to the result of [=process password for init=] given |init|["{{URLPatternInit/password}}"] and |type|.