Arbitrary expressions in new and instanceof
-----
<?php

new ('Foo' . $bar);
new ('Foo' . $bar)($arg);
$obj instanceof ('Foo' . $bar);
-----
array(
    0: Stmt_Expression(
        expr: Expr_New(
            class: Expr_BinaryOp_Concat(
                left: Scalar_String(
                    value: Foo
                )
                right: Expr_Variable(
                    name: bar
                )
            )
            args: array(
            )
        )
    )
    1: Stmt_Expression(
        expr: Expr_New(
            class: Expr_BinaryOp_Concat(
                left: Scalar_String(
                    value: Foo
                )
                right: Expr_Variable(
                    name: bar
                )
            )
            args: array(
                0: Arg(
                    name: null
                    value: Expr_Variable(
                        name: arg
                    )
                    byRef: false
                    unpack: false
                )
            )
        )
    )
    2: Stmt_Expression(
        expr: Expr_Instanceof(
            expr: Expr_Variable(
                name: obj
            )
            class: Expr_BinaryOp_Concat(
                left: Scalar_String(
                    value: Foo
                )
                right: Expr_Variable(
                    name: bar
                )
            )
        )
    )
)