mshtml: Fixed getElementsByTagName for comment elements.

dlls/mshtml/htmlelem.c

@@ -3101,6 +3101,11 @@ static HRESULT WINAPI HTMLElement2_getElementsByTagName(IHTMLElement2 *iface, BS
 
     TRACE("(%p)->(%s %p)\n", This, debugstr_w(v), pelColl);
 
+    if(!This->nselem) {
+        *pelColl = create_collection_from_htmlcol(This->node.doc, NULL);
+        return S_OK;
+    }
+
     nsAString_InitDepend(&tag_str, v);
     nsres = nsIDOMHTMLElement_GetElementsByTagName(This->nselem, &tag_str, &nscol);
     nsAString_Finish(&tag_str);

dlls/mshtml/tests/dom.c

@@ -9468,6 +9468,8 @@ static void test_create_elems(IHTMLDocument2 *doc)
             test_comment_text((IUnknown*)node2, "<!--testing-->");
             IHTMLDOMNode_Release(node2);
 
+            test_elem_getelembytag((IUnknown*)comment, ET_COMMENT, 0, NULL);
+
             IHTMLDOMNode_Release(comment);
         }