Per html spec, the disclosure triangle can be generated via "display:
list-item", I removed the code to generate the triangle in
SummaryFrame::SetInitialChildList(). That is, when a web page set
"display: block" to the summary, the triangle will disappear, too.
Now SummaryFrame does nothing and is going to be removed in Part 2.
Also summary element should not increment the counter as hinted as
"counter-increment: list-item 0" in the spec. Hence the change in
nsBlockFrame::RenumberListsFor().
The rendering hint in html spec:
https://html.spec.whatwg.org/multipage/rendering.html#the-details-and-summary-elements
MozReview-Commit-ID: DELGYFe3zGX
--HG--
rename : layout/reftests/details-summary/open-summary-block-style.html => layout/reftests/details-summary/open-summary-block-style-ref.html
extra : rebase_source : 4bd5493fb6a1108eea31aef1d89f563f781b753f
Ting-Yu Lin