Stub files: style shouldn't change when inside "if" statements

[Akuli]

Describe the style change

In stub files (.pyi), do not add/remove blank lines depending on whether code is under if statements.

Examples in the current Black style

class A:
    def foo(self) -> None: ...

class B:
    def foo(self) -> None: ...

if sys.platform == "linux":
    class A:
        def foo(self) -> None: ...
    class B:
        def foo(self) -> None: ...

Desired style

class A:
    def foo(self) -> None: ...

class B:
    def foo(self) -> None: ...

if sys.platform == "linux":
    class A:
        def foo(self) -> None: ...

    class B:
        def foo(self) -> None: ...

Additional context

The current behavior makes many typeshed PRs unreadable. When reviewing PRs like this, I usually have to recreate the changes of the PR myself and diff my results against what's in the PR.

[hauntsaninja]

:-) I went through the exact same steps as you and filed #2784 an hour ago