Spellchecking compiler comments

This PR cleans up the rest of the spelling mistakes in the compiler comments. This PR does not change any literal or code spelling issues.

compiler/rustc_parse/src/parser/expr.rs

@@ -276,7 +276,7 @@ impl<'a> Parser<'a> {
                 lhs = self.parse_assoc_op_ascribe(lhs, lhs_span)?;
                 continue;
             } else if op == AssocOp::DotDot || op == AssocOp::DotDotEq {
-                // If we didn’t have to handle `x..`/`x..=`, it would be pretty easy to
+                // If we did not have to handle `x..`/`x..=`, it would be pretty easy to
                 // generalise it to the Fixity::None code.
                 lhs = self.parse_range_expr(prec, lhs, op, cur_op_span)?;
                 break;