[parser] Parse only modifiers of actual methods (#10594)

* Parse only modifiers of actual methods

* Throw question token if is used before the real name

packages/babel-parser/src/parser/statement.js

@@ -1348,6 +1348,7 @@ export default class StatementParser extends ExpressionParser {
     const isPrivate = key.type === "PrivateName";
     // Check the key is not a computed expression or string literal.
     const isSimple = key.type === "Identifier";
+    const maybeQuestionTokenStart = this.state.start;
 
     this.parsePostMemberNameModifiers(publicMember);
 
@@ -1403,6 +1404,10 @@ export default class StatementParser extends ExpressionParser {
       // an async method
       const isGenerator = this.eat(tt.star);
 
+      if (publicMember.optional) {
+        this.unexpected(maybeQuestionTokenStart);
+      }
+
       method.kind = "method";
       // The so-called parsed name would have been "async": get the real name.
       this.parseClassPropertyName(method);