Add min specialisation for RangeFrom and last for RangeInclusive

Author: varkor

src/libcore/iter/range.rs

@@ -305,6 +305,11 @@ impl<A: Step> Iterator for ops::RangeFrom<A> {
         self.start = plus_n.add_one();
         Some(plus_n)
     }
+
+    #[inline]
+    fn min(self) -> Option<A> {
+        Some(self.start)
+    }
 }
 
 #[unstable(feature = "fused", issue = "35602")]
@@ -368,6 +373,11 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
         None
     }
 
+    #[inline]
+    fn last(self) -> Option<A> {
+        Some(self.end)
+    }
+
     #[inline]
     fn min(self) -> Option<A> {
         Some(self.start)