Update Custom Elements API to new names.

LayoutTests/fast/dom/custom/element-type.html

Index: LayoutTests/fast/dom/custom/element-type.html
diff --git a/LayoutTests/fast/dom/custom/element-type.html b/LayoutTests/fast/dom/custom/element-type.html
index 0b9bd1f67b611ee06a75fbd1c92e100f4721c3f8..688e66649faf0ffc6685526ec52c8a2240678095 100644
--- a/LayoutTests/fast/dom/custom/element-type.html
+++ b/LayoutTests/fast/dom/custom/element-type.html
@@ -25,11 +25,11 @@ function onCreate(msg) {
 
 var protoX = Object.create(HTMLSpanElement.prototype);
 protoX.createdCallback = onCreate('X');
-var X = document.register('x-x', {extends: 'span', prototype: protoX});
+var X = document.registerElement('x-x', {extends: 'span', prototype: protoX});
 
 var protoY = Object.create(HTMLSpanElement.prototype);
 protoY.createdCallback = onCreate('Y');
-var Y = document.register('x-y', {extends: 'span', prototype: protoY});
+var Y = document.registerElement('x-y', {extends: 'span', prototype: protoY});
 
 var a = document.querySelector('#a');
 shouldBe('a.getAttribute("is")', '"x-y"');