Have getElementsByClassName() / getElementsByTagName*() return an HTMLCollection

Source/core/dom/shadow/ShadowRoot.idl

Index: Source/core/dom/shadow/ShadowRoot.idl
diff --git a/Source/core/dom/shadow/ShadowRoot.idl b/Source/core/dom/shadow/ShadowRoot.idl
index 5173b2bb5e4a92374e3185a4c5cf4f6155aa3844..4a74d5a24fe74e787a51bc7966c58075a4327a3f 100644
--- a/Source/core/dom/shadow/ShadowRoot.idl
+++ b/Source/core/dom/shadow/ShadowRoot.idl
@@ -36,10 +36,10 @@
     [RaisesException] Node cloneNode([Default=Undefined] optional boolean deep);
     Selection getSelection();
     Element getElementById([Default=Undefined] optional DOMString elementId);
-    NodeList getElementsByClassName([Default=Undefined] optional DOMString className);
-    NodeList getElementsByTagName([Default=Undefined] optional DOMString tagName);
-    NodeList getElementsByTagNameNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
-                                    [Default=Undefined] optional DOMString localName);
+    HTMLCollection getElementsByClassName([Default=Undefined] optional DOMString className);
+    HTMLCollection getElementsByTagName([Default=Undefined] optional DOMString tagName);
+    HTMLCollection getElementsByTagNameNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+                                          [Default=Undefined] optional DOMString localName);
 
     Element elementFromPoint([Default=Undefined] optional long x,
                              [Default=Undefined] optional long y);