Revert "questionable patch for TreeHashVector"

This reverts commit 701cc00d08.

eth2/state_processing/tests/tests.rs

@@ -27,7 +27,7 @@ impl ExpectedState {
             ($field_name:ident) => {
                 if self.$field_name.as_ref().map_or(true, |$field_name| {
                     println!("  > Checking {}", stringify!($field_name));
-                    &state.$field_name == $field_name
+                    $field_name == &state.$field_name
                 }) {
                     vec![]
                 } else {

eth2/types/src/tree_hash_vector.rs

@@ -33,12 +33,6 @@ impl<T> DerefMut for TreeHashVector<T> {
     }
 }
 
-impl<T: PartialEq> PartialEq<Vec<T>> for TreeHashVector<T> {
-    fn eq(&self, other: &Vec<T>) -> bool {
-        &self.0 == other
-    }
-}
-
 impl<T> tree_hash::TreeHash for TreeHashVector<T>
 where
     T: TreeHash,