Update spec tests to not be polymorphic

[jfbastien]

From CG-01-26:

Some of the tests import a module called spectest and import a function called print which is overloaded by the embedder. Each import re-imports it with a different signature, but that’s weird because WebAssembly itself doesn’t have overloading. That way you could implement the spectest module in WebAssembly. Same with kinds: a global and function could have the same name.

• Andreas: we could remove it from core tests, but we should still make sure that it validates.
• Luke: I like the principle of being able to implement standard library in WebAssembly.
• Andreas: I would propose removing the print function from the spec tests. We should use assertions instead. It’s no longer relevant. We’ll still test imports, but it doesn’t have to be print.

POLL: unanimous consent to remove polymorphic imports.

AI: Dan to update spec tests to not be polymorphic.

[rossberg]

Refers to WebAssembly/spec#650, PR is in progress at WebAssembly/spec#652.

[binji]

This change landed; closing.