Support the essential part of Shadow DOM v1

third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js

Index: third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js
diff --git a/third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js b/third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js
index 50a8492a4b0122f6bc8f0bd9b9edcc50d3b32305..5f3d1c0c0e02a57c002b2d95f17230510fa32a1a 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js
+++ b/third_party/WebKit/LayoutTests/fast/dom/shadow/resources/shadow-dom.js
@@ -66,6 +66,22 @@ function createDOM(tagName, attributes)
     return element;
 }
 
+function removeWhiteSpaceOnlyTextNodes(node)
+{
+    for (var i = 0; i < node.childNodes.length; i++) {
+        var child = node.childNodes[i];
+        if (child.nodeType === Node.TEXT_NODE && child.nodeValue.trim().length == 0) {
+            node.removeChild(child);
+            i--;
+        } else if (child.nodeType === Node.ELEMENT_NODE || child.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
+            removeWhiteSpaceOnlyTextNodes(child);
+        }
+    }
+    if (node.shadowRoot) {
+        removeWhiteSpaceOnlyTextNodes(node.shadowRoot);
+    }
+}
+
 function convertTemplatesToShadowRootsWithin(node) {
     var nodes = node.querySelectorAll("template");
     for (var i = 0; i < nodes.length; ++i) {