Revert suggestion window size change

Author: estebank

src/librustc_errors/emitter.rs

@@ -462,7 +462,7 @@ pub const MAX_HIGHLIGHT_LINES: usize = 6;
 ///
 /// This should be replaced with a more involved mechanism to output multiline suggestions that
 /// more closely mimmics the regular diagnostic output, where irrelevant code lines are elided.
-pub const MAX_SUGGESTION_HIGHLIGHT_LINES: usize = 20;
+pub const MAX_SUGGESTION_HIGHLIGHT_LINES: usize = 6;
 /// Maximum number of suggestions to be shown
 ///
 /// Arbitrary, but taken from trait import suggestion limit

src/test/ui/issues/issue-22644.stderr

@@ -74,8 +74,7 @@ LL |
 LL |                    as
 LL | 
 LL | 
-LL |                    usize)
-   |
+ ...
 
 error: `<` is interpreted as a start of generic arguments for `usize`, not a shift
   --> $DIR/issue-22644.rs:32:31

src/test/ui/unboxed-closures/unboxed-closure-sugar-lifetime-elision.stderr

@@ -13,8 +13,7 @@ LL |           dyn Foo(&isize) -> &isize                                   >();
 LL |     eq::< dyn for<'a> Foo<(&'a isize,), Output=(&'a isize, &'a isize)>,
 LL |           dyn Foo(&isize) -> (&isize, &isize)                           >();
 LL | 
-LL |     let _: dyn Foo(&isize, &usize) -> &'lifetime usize;
-   |
+ ...
 
 error: aborting due to previous error