Traits map can grow significantly

[anton-trunov]

In the example below each d.contains(Data2 { x: 42, y: 42 }) makes the traits map grow which might slow down compilation time.
We should probably deduplicate the map entries.

contract;

trait Eq {
    fn eq(self, other: Self) -> bool;
}

impl Eq for u64 {
    fn eq(self, other: Self) -> bool {
        __eq(self, other)
    }
}

struct Data2<T, K> {
  x: T,
  y: K
}

impl<T,K> Data2<T,K> {
  fn contains(self, other: Self) -> bool where T: Eq, K: Eq  {
    true
  }
}

fn main() -> u64 {
  let d = Data2 { x: 42, y: 42 };
  d.contains(Data2 { x: 42, y: 42 });
  d.contains(Data2 { x: 42, y: 42 });
  d.contains(Data2 { x: 42, y: 42 });
/// ... and a bunch of d.contains(Data2 { x: 42, y: 42 });

  42
}