Remove contains_item from Range*Ext

`contains` was stabilized in Rust 1.35:
rust-lang/rust#59152

src/inclusive_map.rs

@@ -57,10 +57,7 @@ where
             .filter(|(range_start_wrapper, _value)| {
                 // Does the only candidate range contain
                 // the requested key?
-                //
-                // TODO: Use `contains` once https://github.com/rust-lang/rust/issues/32311
-                // is stabilized.
-                range_start_wrapper.range.contains_item(key)
+                range_start_wrapper.range.contains(key)
             })
             .map(|(range_start_wrapper, value)| (&range_start_wrapper.range, value))
     }

src/map.rs

@@ -56,10 +56,7 @@ where
             .filter(|(range_start_wrapper, _value)| {
                 // Does the only candidate range contain
                 // the requested key?
-                //
-                // TODO: Use `contains` once https://github.com/rust-lang/rust/issues/32311
-                // is stabilized.
-                range_start_wrapper.range.contains_item(key)
+                range_start_wrapper.range.contains(key)
             })
             .map(|(range_start_wrapper, value)| (&range_start_wrapper.range, value))
     }

src/std_ext.rs

@@ -4,9 +4,6 @@ use std::ops::{Range, RangeInclusive};
 pub trait RangeExt<T> {
     fn overlaps(&self, other: &Self) -> bool;
     fn touches(&self, other: &Self) -> bool;
-    // TODO: Remove once https://github.com/rust-lang/rust/issues/32311
-    // is stabilized.
-    fn contains_item(&self, item: &T) -> bool;
 }
 
 impl<T> RangeExt<T> for Range<T>
@@ -26,22 +23,13 @@ where
         // or immediately adjacent.
         max(&self.start, &other.start) <= min(&self.end, &other.end)
     }
-
-    // TODO: Remove once https://github.com/rust-lang/rust/issues/32311
-    // is stabilized.
-    fn contains_item(&self, item: &T) -> bool {
-        *item >= self.start && *item < self.end
-    }
 }
 
 pub trait RangeInclusiveExt<T> {
     fn overlaps(&self, other: &Self) -> bool;
     fn touches(&self, other: &Self) -> bool
     where
         T: StepLite + Bounded + Clone;
-    // TODO: Remove once https://github.com/rust-lang/rust/issues/32311
-    // is stabilized.
-    fn contains_item(&self, item: &T) -> bool;
 }
 
 impl<T> RangeInclusiveExt<T> for RangeInclusive<T>
@@ -76,12 +64,6 @@ where
         };
         max(self.start(), other.start()) <= min(&longer_self_end, &longer_other_end)
     }
-
-    // TODO: Remove once https://github.com/rust-lang/rust/issues/32311
-    // is stabilized.
-    fn contains_item(&self, item: &T) -> bool {
-        *item >= *self.start() && *item <= *self.end()
-    }
 }
 
 /// Minimal version of unstable [Step](std::iter::Step) trait