URLSearchParams: add tests for two-argument delete() and has()

For whatwg/url#735.

url/urlsearchparams-delete.any.js

@@ -61,3 +61,12 @@ test(() => {
   assert_equals(url.pathname, 'space    ');
   assert_equals(url.href, 'data:space    #test');
 }, 'Changing the query of a URL with an opaque path can impact the path if the URL has no fragment');
+
+test(() => {
+  const params = new URLSearchParams();
+  params.append('a', 'b');
+  params.append('a', 'c');
+  params.append('a', 'd');
+  params.delete('a', 'c');
+  assert_equals(params.toString(), 'a=b&a=d');
+}, "Two-argument delete()");

url/urlsearchparams-has.any.js

@@ -22,3 +22,16 @@ test(function() {
     params.delete('first');
     assert_false(params.has('first'), 'Search params object has no name "first"');
 }, 'has() following delete()');
+
+test(() => {
+  const params = new URLSearchParams("a=b&a=d&c&e&");
+  assert_true(params.has('a', 'b'));
+  assert_false(params.has('a', 'c'));
+  assert_true(params.has('a', 'd'));
+  assert_true(params.has('e', ''));
+  params.append('first', null);
+  assert_false(params.has('first', ''));
+  assert_true(params.has('first', 'null'));
+  params.delete('a', 'b');
+  assert_true(params.has('a', 'd'));
+}, "Two-argument has()");