:root[dir="rtl"] does not work with shimed CSS properties

[dfreedm]

Description

Live Demo

With useNativeCSSProperties
http://jsbin.com/zoloru/edit?html,output

Without:
http://jsbin.com/qezehez/edit?html,output

[eeid26]

Actually there is another annoying bug that makes supporting rtl in polymer not as easy as it should be.
(I already reported the bug before and it was marked as a duplicate and it wasn't really.)

a rule like
:host([some-attribute]):host-context([dir='rtl'])
works in shadow dom and it does not work in shady dom.

Example showing the bug using a modified version of your Example:
with shadow dom (Works)
http://jsbin.com/dutihahuye/edit?html,output

with shady dom (Does not work)
http://jsbin.com/hemopediyi/edit?html,output

[helenxywu]

@eeid26 Have you tried the workaround here webcomponents/webcomponentsjs#16?

[eeid26]

Thank you @helenxywu
Yes I tried it before and I tried it now and it did not work for me. Even the example in the link did not work for me.

[helenxywu]

yea you're right I'm filing another bug for that. #3904