DOMException: Failed to read the 'cssRules' property from 'CSSStyleSheet'

[cbfrank]

As of the recent changes from chrome
https://chromium.googlesource.com/chromium/src/+/a4ebe08c91e29140e700c7bae9b94f27a786d1ca
(more detail information: https://stackoverflow.com/questions/48753691/cannot-access-cssrules-from-local-css-file-in-chrome-64/49160760#49160760)
so even the css is loaded from cdn, the check of css exports always failed.
an "origin-clean" (see https://www.w3.org/TR/cssom-1/#concept-css-style-sheet-origin-clean-flag) attribute should be added to the element to make the check works on latest Chrome browser.