Fix class expression indentation

[saschanaz]

Fixes #4580

Current:

class Foo extends (
    class

    {
    bar() { }
    }
)

Fix:

class Foo extends (
    class {
        bar() { }
    }
)

[vladima]

👍 LGTM

[vladima]

Thanks @saschanaz!

[mhegazy]

We should merge this into release-1.6