Address minor nit in CSSSelectorParser::consumePseudo()

https://bugs.webkit.org/show_bug.cgi?id=270081

Reviewed by Antti Koivisto.

As it's already been verified that token is either an IdentToken or
FunctionToken, and IdentToken has been dealt with at this point, it can
only be a FunctionToken.

* Source/WebCore/css/parser/CSSSelectorParser.cpp:
(WebCore::CSSSelectorParser::consumePseudo):

Canonical link: https://commits.webkit.org/275323@main

Source/WebCore/css/parser/CSSSelectorParser.cpp

@@ -750,10 +750,9 @@ std::unique_ptr<MutableCSSSelector> CSSSelectorParser::consumePseudo(CSSParserTo
         return selector;
     }
 
+    ASSERT(token.type() == FunctionToken);
     CSSParserTokenRange block = range.consumeBlock();
     block.consumeWhitespace();
-    if (token.type() != FunctionToken)
-        return nullptr;
 
     if (selector->match() == CSSSelector::Match::PseudoClass) {
         switch (selector->pseudoClass()) {