CSS line-height values should be unitless - forms.css

[ianbelanger]

As outlined in #44643, CSS line-height values should be unitless unless necessary to be defined as a specific pixel value. It was suggested that we break up 44643 by stylesheet in order to better track them.

This ticket covers much of wp-admin/css/forms.css, see patch notes below

Note: The patch was tested only on a Windows machine in Chrome, Firefox, IE11 and Edge. As per https://core.trac.wordpress.org/ticket/44643#comment:23 it should probably be tested on other OS's and supported browsers.

Patch Notes:

Unable to find selectors in the DOM

line 757 - .tool-box .title
line 823 - .pressthis-bookmarklet, .pressthis-bookmarklet:hover, .pressthis-bookmarklet:focus, .pressthis-bookmarklet:active

[ianbelanger]

Updates patch with more precise line-height calculations

[SergeyBiryukov]

In 45464:

CSS Coding Standards: Use unitless values for line-height in wp-admin/css/forms.css.

Props ianbelanger, pbiron, afercia.
Fixes #46512. See #44643.