Don't create layout objects for children of display-none iframes.

third_party/WebKit/LayoutTests/paint/invalidation/shift-relative-positioned-container-with-image-addition-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [785, 829],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow HTML",
@@ skipping 71 matching lines @@
     },
     {
       "object": "LayoutImage IMG",
       "reason": "bounds change"
     },
     {
       "object": "LayoutText #text",
       "reason": "location change"
     },
     {
-      "object": "VerticalScrollbar",
-      "reason": "scroll"
-    },
-    {
       "object": "LayoutView #document",
       "reason": "style change"
     },
     {
       "object": "LayoutBlockFlow HTML",
       "reason": "layoutObject insertion"
     },
     {
       "object": "LayoutBlockFlow BODY",
       "reason": "layoutObject insertion"
     }
   ]
 }