[4.0] Use double colon for pseudo elements

[C-Lodder]

Summary of Changes

Use double colon for pseudo elements

Testing Instructions

Code review

[dgrammatiko]

I should be blamed for this...

[brianteeman]

it is actually optional for this pseudo element but I am happy to blame @dgrammatiko

[C-Lodder]

@brianteeman Still optional but better to distinguish between a pseudo element and pseudo class. You also never know if browsers will drop single colons for pseudo elements in the future.

[brianteeman]

I have tested this item ✅ successfully on 15035c7

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[Quy]

I have tested this item ✅ successfully on 15035c7

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/26088.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/26088.}

[wilsonge]

Thanks!

[ghazal]

I have tested this item 🔴 unsuccessfully on f24c441

Just tested this on a fresh install with Composer and NPM, and I got this error in the Terminal:

       The selector ".fa-dot-circle::before" was not found.
       Use "@extend .fa-dot-circle::before !optional" if the extend should be able to fail.
        on line 22 of build/media_source/system/scss/_icomoon.scss
>>     @extend .#{$fa-css-prefix}-dot-circle::before; 

compile-css could not proceed.<hr /><sub>This comment was created with the <a href="https://github.com/joomla/jissues">J!Tracker Application</a> at <a href="https://issues.joomla.org/tracker/joomla-cms/26088">issues.joomla.org/tracker/joomla-cms/26088</a>.</sub>

[wilsonge]

Thanks!

Fixed with 4a5a2fb (clearly no one actually tested)