Remove support for custom pseudo elements.

LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html

Index: LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html
diff --git a/LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html b/LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html
index ccda1a6f9431708eea9624247c929055ba8145ba..d75d8d738368ab40cd7fff91301a3fc95c7b1b9a 100644
--- a/LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html
+++ b/LayoutTests/fast/dom/shadow/custom-pseudo-in-selector-api.html
@@ -18,20 +18,6 @@ shouldBeNull('sandbox.firstChild.querySelector("input[type=\'search\']::-webkit-
 shouldBe('sandbox.firstChild.querySelectorAll("input[type=\'search\']::-webkit-search-decoration").length', '0');
 
 sandbox.innerHTML = '';
-
-sandbox.appendChild(
-    createDOM('div', {'id': 'host'},
-        createShadowRoot(
-            createDOM('div', {'pseudo': 'x-pseudo', 'part': 'x-part'}))));
-
-shouldBeFalse('sandbox.firstChild.webkitMatchesSelector("div::x-pseudo")');
-shouldBeFalse('sandbox.firstChild.webkitMatchesSelector("div::x-part")');
-shouldBeNull('sandbox.firstChild.querySelector("div::x-pseudo")');
-shouldBeNull('sandbox.firstChild.querySelector("div::x-part")');
-shouldBe('sandbox.firstChild.querySelectorAll("div::x-pseudo").length', '0');
-shouldBe('sandbox.firstChild.querySelectorAll("div::x-part").length', '0');
-
-sandbox.innerHTML = '';
 </script>
 </body>
 </html>