Set `in` to `true` when parsing AssignmentExpression in ConditionalExpression (#2386)

This Pull Request fixes the following:

- Set `in` to `true` when parsing AssignmentExpression in ConditionalExpression

boa_engine/src/syntax/parser/expression/assignment/conditional.rs

@@ -80,13 +80,9 @@ where
         if let Some(tok) = cursor.peek(0, interner)? {
             if tok.kind() == &TokenKind::Punctuator(Punctuator::Question) {
                 cursor.next(interner)?.expect("? character vanished"); // Consume the token.
-                let then_clause = AssignmentExpression::new(
-                    None,
-                    self.allow_in,
-                    self.allow_yield,
-                    self.allow_await,
-                )
-                .parse(cursor, interner)?;
+                let then_clause =
+                    AssignmentExpression::new(None, true, self.allow_yield, self.allow_await)
+                        .parse(cursor, interner)?;
                 cursor.expect(Punctuator::Colon, "conditional expression", interner)?;
 
                 let else_clause = AssignmentExpression::new(