Do not force sizing groups to display inline-block (#2044)

Fix #1788 by removing `display:inline-block` rule from `.sizing`.
I don't see why a sizing change cares about the display mode, and it
fixes the interaction between `makeVList` and sizing commands.
It should also allow me to remove a `.sizing { width:min-content }` rule
that I had to add in #1787.

src/katex.less

@@ -304,8 +304,6 @@
 
     .sizing,
     .fontsize-ensurer {
-        display: inline-block;
-
         @size1: 0.5;
         @size2: 0.6;
         @size3: 0.7;