Remove css/construct-stylesheets/ directory (with a single test)

In https://github.com/web-platform-tests/wpt/pull/29414,
interfaces/construct-stylesheets.idl is being removed and the
same bits have been added to interfaces/cssom.idl. In order to not break
the tests temporarily, the test using construct-stylesheets.idl should
be removed.
diff --git a/css/construct-stylesheets/META.yml b/css/construct-stylesheets/META.yml
deleted file mode 100644
index 9ffc2c6..0000000
--- a/css/construct-stylesheets/META.yml
+++ /dev/null
@@ -1,5 +0,0 @@
-spec: https://wicg.github.io/construct-stylesheets/
-suggested_reviewers:
-  - ericwilligers
-  - rakina
-  - tabatkins
diff --git a/css/construct-stylesheets/idlharness.html b/css/construct-stylesheets/idlharness.html
deleted file mode 100644
index 85de760..0000000
--- a/css/construct-stylesheets/idlharness.html
+++ /dev/null
@@ -1,25 +0,0 @@
-<!doctype html>
-<title>Constructable Stylesheet Objects IDL tests</title>
-<link rel="help" href="https://wicg.github.io/construct-stylesheets/">
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<script src="/resources/WebIDLParser.js"></script>
-<script src="/resources/idlharness.js"></script>
-<div id="shadowHost"></div>
-<script>
-  'use strict';
-
-  idl_test(
-    ['construct-stylesheets'],
-    ['cssom', 'dom'],
-    idl_array => {
-      idl_array.add_objects({
-        CSSStyleSheet: ['new CSSStyleSheet()'],
-        Document: ['document'],
-        ShadowRoot: ['shadowRoot'],
-      });
-      const shadowHost = document.getElementById('shadowHost');
-      self.shadowRoot = shadowHost.attachShadow({mode: 'open'});
-    }
-  );
-</script>