[Webkit-unassigned] [Bug 134630] New: Make unicode-bidi:isolate the default for an element with a dir attribute (instead of unicode-bidi:embed)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=134630

           Summary: Make unicode-bidi:isolate the default for an element
                    with a dir attribute (instead of unicode-bidi:embed)
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: NEW
          Severity: Major
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: ishida at w3.org
                CC: aharon at google.com, ishida at w3.org


The HTML5 spec changes the semantics of the dir attribute to use unicode-bidi:isolate instead of unicode-bidi:embed (on all elements except BDO), and unicode-bidi: isolate-override instead of unicode-bidi:bidi-override on BDO.

Here is a link to the relevant section of the HTML5 spec and the CSS involved:
http://www.w3.org/TR/html5/rendering.html#bidi-rendering

Similarly, the definition of the dir attribute in the HTML5 spec speaks of it making the element's content "directionally isolated"; see http://www.w3.org/TR/html5/dom.html#the-dir-attribute

This is a very important change that should make it easier to author bidi pages. It was proposed and extensively discussed by the W3C i18n WG (http://www.w3.org/International/wiki/Html-bidi-isolation), and then by the WHATWG and HTML5 WG (https://www.w3.org/Bugs/Public/show_bug.cgi?id=23260).

It is also a very easily implemented change - just a change in the default CSS.

The change is not backward compatible, but it is very close to the behavior of IE 8 through IE 11. The bodies mentioned above were well aware of the lack of backward compatibility, but approved the change nonetheless because of its benefits going forward.

It is now the standard.

(Chrome's implementation of unicode-bidi:isolate (prefixed as -webkit-isolate) has undergone a number of bug fixes over the past year and a half and is currently stable and, as far as Aharon Lanin knows, bug-free. For the past three months, all Google Web Search and Google Maps pages have already included a piece of CSS (very similar to that in http://www.w3.org/TR/html5/rendering.html#bidi-rendering) that implements this behavior, i.e. applies isolation to all elements with the dir attribute. It fixed a number of problems in those pages, and did not cause any problems. In a couple of cases, it caused a visible change in the display that was considered to be neither good nor bad, just different.)

It is time to implement the HTML5 spec and make this Webkit's default behavior for all pages.

BTW, this also requires a fix for bug 124146, for those cases affected. (This has already been fixed in Chrome, and Aharon Lanin can provide help if needed.)

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