Support bidi isolation for elements with dir attributes, and for bdi
This is a specific request for Edge to support bidi isolation per the HTML specification where the dir attribute and the bdi element are used. The wording in the request for dir=auto  is equally valid here.
Support for isolation is really a fundamental requirement for languages using Arabic and Hebrew and other scripts such as Thaana, Syriac, N'Ko, etc. Note also that the Arabic script is the second most widely used script around the world after the Latin script, so this affects a lot of people. And the lack of isolation is not an edge-case problem (see worked examples at http://w3c.github.io/i18n-drafts/articles/inline-bidi-markup/index.en#staticexamples). It's hard to understand why Edge still doesn't support isolation for any use of the dir attribute and for bdi per the HTML standard. Unfortunately, the best recommendation for users of RTL scripts around the world is currently to use another browser than Edge.
This is important for static HTML document use, but is especially problematic for apps and other dynamic environments.
Here are some test results that may help:
dir isolation https://www.w3.org/International/tests/repo/results/the-dir-attribute-isolation
(click on the links in the left-most column to run the tests)
To better understand the issues read:
https://www.w3.org/International/articles/inline-bidi-markup/uba-basics (bidi primer)
http://w3c.github.io/i18n-drafts/articles/inline-bidi-markup/index.en (explanations and examples of problems)
Although the W3C and the HTML spec recommend the use of markup rather than CSS for managing text direction for RTL scripts, it would also be good to support unicode-bidi: isolate.