deconflict with builtins

[tanhauhau]

Fixes #3724

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Tests

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[Rich-Harris]

Thank you. I'm confused about why each_anchor is now being turned into each_1_anchor — any ideas? Is it avoidable?

[tanhauhau]

because each is a builtin method name, that's why it's suffixed to each_1, which concatenate with _anchor.

I'm not sure how to register var as each_anchor instead, would lead to more code change