STR: 1. Start a clean profile 2. hit ctrl + shift + J 2. Load the testcase Expected result: The page should load cleanly Actual result: Error: InvalidAccessError: A parameter or an operation is not supported by the underlying object Source File: https://bug800282.bugzilla.mozilla.org/attachment.cgi?id=670289 Line: 8 Nightly: Last good: 2012-06-05 First bad: 2012-06-06 http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a7a905fd70d5&tochange=6338a8988917 Inbound: Last good: 2012-06-04 First bad: 2012-06-05 http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=778ba119ded6&tochange=f56e2197d9cd Intersection: Last good: a7a905fd70d5 First bad: f56e2197d9cd http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a7a905fd70d5&tochange=f56e2197d9cd
This isn't an arbitrary attribute. It's a very particular attribute. It's an attribute defined in the microdata API, which landed during your regression range. And the spec for what happens when setting .itemValue is at http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#dom-itemvalue and says: If the element has no itemprop attribute The attribute must return null on getting and must throw an InvalidAccessError exception on setting. which is what happens in your attached testcase. No itemprop attribute means we throw an InvalidAccessError.
Marking invalid, but please do reopen if there's something I missed here.