[css-pseudo] Fix WPT expectations for marker-font-variant-numeric-*

The marker-font-variant-numeric-default.html test is supposedly passing
in Chromium according to Chromium, but not according to wpt.fyi. The
reason is that in certain configurations, the test may look slightly
different than the reference due to font anti-aliasing.

The marker-font-variant-numeric-normal.html fails in all browsers due to
lack of support for nested ::marker selectors, but there are also some
differences in the parts that should actually match the reference.

This patch fixes both issues.

Bug: 457718
Change-Id: Id646b7810aed18441e1c7b37ad7bb1a37877be2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980174Reviewed-by: Manuel Rego <rego@igalia.com>
Commit-Queue: Oriol Brufau <obrufau@igalia.com>
Cr-Commit-Position: refs/heads/master@{#727963}

third_party/blink/web_tests/external/wpt/css/css-pseudo/marker-font-variant-numeric-default-ref.html

@@ -3,6 +3,7 @@
 <title>CSS Reftest Reference</title>
 <link rel="author" title="Oriol Brufau" href="mailto:obrufau@igalia.com" />
 <link rel="mismatch" href="marker-font-variant-numeric-normal-ref.html">
+<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
 <style>
 @font-face {
   /* This font looks different with 'font-variant-numeric: tabular-nums' */
@@ -17,19 +18,13 @@ ol {
   list-style-position: inside;
   font-family: "Exo 2";
 }
-span {
+li:first-child::after {
+  content: 'X X X X X X X X X';
   display: inline-block;
+  font: 25px/1 Ahem;
   vertical-align: top;
-}
-li:first-child::before {
-  content: '\200B'; /* zero-width space */
-}
-li:first-child::after {
-  content: '';
-  position: absolute;
-  height: 225px;
+  height: 0;
   width: 25px;
-  background: black;
 }
 </style>
 <ol>

third_party/blink/web_tests/external/wpt/css/css-pseudo/marker-font-variant-numeric-normal-ref.html

@@ -3,6 +3,7 @@
 <title>CSS Reftest Reference</title>
 <link rel="author" title="Oriol Brufau" href="mailto:obrufau@igalia.com" />
 <link rel="mismatch" href="marker-font-variant-numeric-default-ref.html">
+<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
 <style>
 @font-face {
   /* This font looks different with 'font-variant-numeric: tabular-nums' */
@@ -19,10 +20,10 @@ ol {
 }
 span {
   display: inline-block;
+  font: 25px/1 Ahem;
   vertical-align: top;
   width: 25px;
   height: 25px;
-  background: black;
 }
 </style>
 <ol>