Use parseFloat() to parse CSS pixels values in two WPT

Two WPT use CSSNumericValue.parse() to parse CSS pixel values, which
makes the tests basically Chrome-only. This patch changes them to use
parseFloat() directly so that other browsers can pass.

Bug: 441925
Change-Id: I01d6d2999cf4266bd6d3bda521d2bdfc8732ab7c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2031932Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737036}

third_party/blink/web_tests/external/wpt/css/css-values/ch-pseudo-recalc-on-font-load.html

@@ -41,10 +41,10 @@
 
 <script>
 function parseFontSizeInPx(element, pseudoElement) {
-  const value = CSSNumericValue.parse(getComputedStyle(element, pseudoElement).fontSize);
-  if (!value || !(value instanceof CSSUnitValue) || value.unit !== 'px')
-    throw 'Cannot parse width in pixels';
-  return value.value;
+  const value = getComputedStyle(element, pseudoElement).fontSize;
+  if (!value.endsWith('px'))
+    return NaN;
+  return parseFloat(value);
 }
 
 const testCases = ['before', 'after', 'first-letter', 'first-line', 'marker'];

third_party/blink/web_tests/external/wpt/css/css-values/ch-recalc-on-font-load.html

@@ -28,10 +28,10 @@
 
 <script>
 function parseWidthInPx(element) {
-  const value = CSSNumericValue.parse(getComputedStyle(element).width);
-  if (!value || !(value instanceof CSSUnitValue) || value.unit !== 'px')
-    throw 'Cannot parse width in pixels';
-  return value.value;
+  const value = getComputedStyle(element).width;
+  if (!value.endsWith('px'))
+    return NaN;
+  return parseFloat(value);
 }
 
 const testCases = document.querySelectorAll('.test');