Add <dimension-token> type-checking to CSSNumericValue::parse()

This patch implements a recent spec bug fix:

w3c/css-houdini-drafts#1065

Fixed: 1291603
Change-Id: I3adae8148dd47b24d4516448e492daccce7ecd91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3425673
Auto-Submit: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#965351}

third_party/blink/renderer/core/css/cssom/css_numeric_value.cc

@@ -252,7 +252,7 @@ CSSNumericValue* CSSNumericValue::parse(const String& css_text,
     case kPercentageToken:
     case kDimensionToken: {
       const auto token = range.ConsumeIncludingWhitespace();
-      if (!range.AtEnd())
+      if (!range.AtEnd() || !IsValidUnit(token.GetUnitType()))
         break;
       return CSSUnitValue::Create(token.NumericValue(), token.GetUnitType());
     }

third_party/blink/web_tests/external/wpt/css/css-typed-om/stylevalue-subclasses/numeric-objects/parse.tentative.html

@@ -23,6 +23,10 @@
   assert_throws_dom("SyntaxError", () => CSSNumericValue.parse('calc(calc(1px * 2s) + 3%)'));
 }, 'Parsing a calc with incompatible units throws a SyntaxError');
 
+test(() => {
+  assert_throws_dom("SyntaxError", () => CSSNumericValue.parse('1xyz'));
+}, 'Parsing a <dimension-token> with invalid units throws a SyntaxError');
+
 test(() => {
   assert_style_value_equals(new CSSUnitValue(1, 'px'), CSSNumericValue.parse(' 1px  '));
 }, 'Parsing ignores surrounding spaces');