Prevent SVG shrinking (#25652)

This will prevent the most common cases of SVG shrinking because lack of
space. I evaluated multiple options and this seems to be the one with
the least impact in size and processing cost, so I went with it.

Unfortunately, CSS can not dynamically convert `16` obtained from
`attr()` to `16px`, or else a generic solution for all sizes would have
been possible. But a solution is [in
sight](https://developer.mozilla.org/en-US/docs/Web/CSS/attr#type-or-unit)
with `attr(width px)` but no browser supports it currently.

web_src/css/base.css

@@ -375,16 +375,6 @@ progress::-moz-progress-bar {
   opacity: 1 !important;
 }
 
-.svg {
-  display: inline-block;
-  vertical-align: text-top;
-  fill: currentcolor;
-}
-
-.middle .svg {
-  vertical-align: middle;
-}
-
 .unselectable,
 .button,
 .lines-num,