[Tracking Requested - why for this release]: regression 1. http://www.purepeople.com/people/celine-dion_p53 +15 other urls so far. 2. Assertion failure: this != presContext->GetViewportScrollbarStylesOverrideElement() (Leaving behind a raw pointer to this element (as having propagated scrollbar styles) - that's dangerous...), at /builds/worker/workspace/build/src/dom/base/Element.cpp:1878 #01: nsGenericHTMLElement::UnbindFromTree [dom/html/nsGenericHTMLElement.cpp:538] #02: mozilla::dom::Element::UnbindFromTree [dom/base/Element.cpp:1988] #03: nsGenericHTMLElement::UnbindFromTree [dom/html/nsGenericHTMLElement.cpp:538] #04: mozilla::dom::HTMLSharedElement::UnbindFromTree [dom/html/HTMLSharedElement.cpp:292] #05: nsDocument::ResetToURI [dom/base/nsDocument.cpp:2338] #06: nsHTMLDocument::ResetToURI [dom/html/nsHTMLDocument.cpp:253] #07: nsDocument::Reset [mfbt/RefPtr.h:63] #08: nsHTMLDocument::Reset [dom/html/nsHTMLDocument.cpp:240] #09: nsHTMLDocument::Open [xpcom/base/nsCOMPtr.h:796] #10: nsHTMLDocument::Open [dom/html/nsHTMLDocument.cpp:1455] #11: nsHTMLDocument::WriteCommon [dom/html/nsHTMLDocument.cpp:1966] #12: nsHTMLDocument::WriteCommon [dom/bindings/ErrorResult.h:376] #13: mozilla::dom::HTMLDocumentBinding::write [s3:gecko-generated-sources:64b09d1bcd2abe9ccee4a25413be74081dd54eb49ecea5100966e450ab9d7d1ef8391021a6e9a66be64575c60373e5933a077967ab52ca896c5c75ce22defdd5/dom/bindings/HTMLDocumentBinding.cpp::690] #14: mozilla::dom::GenericBindingMethod [dom/bindings/BindingUtils.cpp:3057] Windows, Linux Nighlty 57. Testing locally on Fedora on Release/56 does not assert.

Dupe of bug 1400599?

I don't have access to that bug.

It definitely looks like a dupe.

Mirroring status-firefox57 of bug 1400599.