[Reland #1] Don't create layout objects for children of display-none iframes.

third_party/WebKit/LayoutTests/external/wpt/html/resources/common.js

 /*
 Distributed under both the W3C Test Suite License [1] and the W3C
 3-clause BSD License [2]. To contribute to a W3C Test Suite, see the
 policies and contribution forms [3].
 
 [1] http://www.w3.org/Consortium/Legal/2008/04-testsuite-license
 [2] http://www.w3.org/Consortium/Legal/2008/03-bsd-license
 [3] http://www.w3.org/2004/10/27-testcases
  */
 
@@ skipping 43 matching lines @@
     return d;
 }
 
 function newIFrame(context, src) {
     if (typeof (context) === 'undefined'
             || typeof (context.iframes) !== 'object') {
         assert_unreached('Illegal context object in newIFrame');
     }
 
     var iframe = document.createElement('iframe');
-    iframe.style.display = 'none';
 
     if (typeof (src) != 'undefined') {
         iframe.src = src;
     }
     document.body.appendChild(iframe);
     context.iframes.push(iframe);
 
     assert_true(typeof (iframe.contentWindow) != 'undefined'
             && typeof (iframe.contentWindow.document) != 'undefined'
             && iframe.contentWindow.document != document,
@@ skipping 103 matching lines @@
     }
 }
 
 function checkBodyTemplateContent(d, html, id, nodeName) {
     checkTemplateContent(d, d.body, html, id, nodeName);
 }
 
 function checkHeadTemplateContent(d, html, id, nodeName) {
     checkTemplateContent(d, d.head, html, id, nodeName);
 }