Unreachable imports not ignored in methods

[JukkaL]

The second import xxx as os generates an error, though it's similar to the first import, which doesn't generate an error:

import sys

def f() -> None:
    if sys.platform == 'xyz':  # Nonsensical platform
        import xxx as os  # No error
    else:
        import os

class A:
    def g(self) -> None:
        if sys.platform == 'xyz':
            import xxx as os  # Error
        else:
            import os

The culprit is semantic analyzer pass 1, which only recurses into top-level functions but not into methods.

[JukkaL]

This has been fixed in the new semantic analyzer.