Fully stabilize NLL

tests/ui/crashes/ice-6256.stderr

@@ -1,18 +1,14 @@
-error[E0308]: mismatched types
-  --> $DIR/ice-6256.rs:13:28
+error[E0521]: borrowed data escapes outside of closure
+  --> $DIR/ice-6256.rs:13:26
    |
 LL |     let f = |x: &dyn TT| x.func(); //[default]~ ERROR: mismatched types
-   |                            ^^^^ lifetime mismatch
-   |
-   = note: expected reference `&(dyn TT + 'static)`
-              found reference `&dyn TT`
-note: the anonymous lifetime #1 defined here...
-  --> $DIR/ice-6256.rs:13:13
-   |
-LL |     let f = |x: &dyn TT| x.func(); //[default]~ ERROR: mismatched types
-   |             ^^^^^^^^^^^^^^^^^^^^^
-   = note: ...does not necessarily outlive the static lifetime
+   |              -  -        ^^^^^^^^
+   |              |  |        |
+   |              |  |        `x` escapes the closure body here
+   |              |  |        argument requires that `'1` must outlive `'static`
+   |              |  let's call the lifetime of this reference `'1`
+   |              `x` is a reference that is only valid in the closure body
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0521`.