address review comments

src/test/run-pass/cast-rfc0401.rs

@@ -88,7 +88,7 @@ fn main()
     assert_eq!(u as *const u8, p as *const u8);
     assert_eq!(u as *const u16, p as *const u16);
 
-    // ptr-ptr-cast (both vk=Length)
+    // ptr-ptr-cast (Length vtables)
     let mut l : [u8; 2] = [0,1];
     let w: *mut [u16; 2] = &mut l as *mut [u8; 2] as *mut _;
     let w: *mut [u16] = unsafe {&mut *w};
@@ -99,7 +99,7 @@ fn main()
     let l_via_str = unsafe{&*(s as *const [u8])};
     assert_eq!(&l, l_via_str);
 
-    // ptr-ptr-cast (both vk=Length, check length is preserved)
+    // ptr-ptr-cast (Length vtables, check length is preserved)
     let l: [[u8; 3]; 2] = [[3, 2, 6], [4, 5, 1]];
     let p: *const [[u8; 3]] = &l;
     let p: &[[u8; 2]] = unsafe {&*(p as *const [[u8; 2]])};