Add regression tests for instanceof #4525
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This PR contains:
Are tests included?
Breaking Changes?
List any relevant issue numbers:
#4524
Description
To not go empty handed after the explorations in #4524, this PR adds the regression tests created there so that we have them available when we have another attempt at tree-shaking instanceof.
The core of the problem is that there are quite legitimate use cases where the only usage of a class is in the left side of an instanceof, most importantly if the left side is a function parameter and the instance is passed as a parameter to that function.
One possible approach would be to actively determine if
But that would require quite a bit of new infrastructure just to support this, so I would rather hold off on this until we have a real use case.