ISSUE: Trait method .powi not being considered because <f32>::powi is found

Needs to search for trait methods first.
- But that falls into problems when the trait method isn't the correct method!
  - E.g. `impl Iterator for Parser` ... `impl Parser { fn position(&mut self) }`


References:
- `rustc-nightly/src/libfmt_macros/lib.rs` line 272
  - Requires that `<Parser>::position` be called not `Iterator::position`
- `rustc-nightly/src/vendor/num-traits/src/lib.rs` line 308
  - Requires that `Float::powi` be chosen for inferrence to succeed