Missing parens for ClassExpression with decorators

[fisker]

Prettier 2.5.1
Playground link

--parser babel

Input:

(@f() class {});

Output:

@f()
class {};

Second Output:

SyntaxError: A class name is required. (2:7)
  1 | @f()
> 2 | class {};
    |       ^
  3 |

Expected behavior:

Should keep parens

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Found this during #12241, when fixing this, should add this test back.