Specification: https://webidl.spec.whatwg.org/#abstract-opdef-converttoint
Gecko's implementation: https://searchfox.org/firefox-main/rev/aee7c0f24f488cd7f5a835803b48dd0c0cb2fd5f/dom/bindings/PrimitiveConversions.h#225-269
Servo's implementation: https://github.com/servo/mozjs/blob/4d290e8a270f1bf6cc18aa5860427243a39cc128/mozjs/src/conversions.rs#L227-L244

We just end up using f32 as i64, which is incorrect. We should port the rest of the logic from Gecko; the resulting implementation should make the remaining tests in

Tests: ./mach test-wpt tests/wpt/tests/FileAPI/blob/Blob-slice.any.js