Remove the support of multiple shadow roots with a user agent shadow root

third_party/WebKit/LayoutTests/svg/dom/custom-elements.html

Index: third_party/WebKit/LayoutTests/svg/dom/custom-elements.html
diff --git a/third_party/WebKit/LayoutTests/svg/dom/custom-elements.html b/third_party/WebKit/LayoutTests/svg/dom/custom-elements.html
index 9c08e0c3fe99d596eb8915330a874f2ff2b45e79..f1eae7fbf69825bc8e1c551d3b7a1724d5bbb4ba 100644
--- a/third_party/WebKit/LayoutTests/svg/dom/custom-elements.html
+++ b/third_party/WebKit/LayoutTests/svg/dom/custom-elements.html
@@ -12,18 +12,6 @@ document.registerElement("x-g", { extends: "g", prototype: {
   }
 });
 
-document.registerElement("x-use", { extends: "use", prototype: {
-    __proto__: SVGUseElement.prototype,
-    createdCallback: function() {
-      var greenBox = document.createElementNS('http://www.w3.org/2000/svg', 'rect');
-      greenBox.setAttribute('width', '20');
-      greenBox.setAttribute('height', '20');
-      greenBox.setAttribute('fill', 'green');
-      this.createShadowRoot().appendChild(greenBox);
-    }
-  }
-});
-
 document.registerElement("x-green", { extends: "g", prototype: {
     __proto__: SVGGElement.prototype,
     createdCallback: function() {
@@ -55,12 +43,6 @@ document.registerElement("x-pass", { extends: "text", prototype: {
 </svg><br>
 
 <svg width="30px" height="30px" xmlns="http://www.w3.org/2000/svg">
-  <use is="x-use">
-    <rect width="100" height="100" fill="red"></rect>
-  </use>
-</svg><br>
-
-<svg width="30px" height="30px" xmlns="http://www.w3.org/2000/svg">
   <defs>
     <rect id="use-green" width="20" height="20" fill="green"></rect>
   </defs>
@@ -68,13 +50,6 @@ document.registerElement("x-pass", { extends: "text", prototype: {
 </svg><br>
 
 <svg width="30px" height="30px" xmlns="http://www.w3.org/2000/svg">
-  <defs>
-    <rect id="use-red" width="100" height="10" fill="red"></rect>
-  </defs>
-  <use is="x-use" xlink:href="#use-red"></use>
-</svg><br>
-
-<svg width="30px" height="30px" xmlns="http://www.w3.org/2000/svg">
   <g is="x-green">
     <rect width="100" height="100" fill="red"></rect>
   </g>
@@ -82,4 +57,4 @@ document.registerElement("x-pass", { extends: "text", prototype: {
 
 <svg width="30px" height="30px" xmlns="http://www.w3.org/2000/svg">
   <text is="x-pass" font-size="10px" y="20">FAIL</text>
-</svg>
+</svg>