Pull in linter 0.1.8.

* Protects against errors in linting invalid source (#24910).
* Adds `avoid_empty_else` lint rule (dart-lang/sdk#224936).

[email protected]

Review URL: https://codereview.chromium.org/1472403002 .

Author: pq

DEPS

@@ -67,7 +67,7 @@ vars = {
   "intl_rev": "@32047558bd220a53c1f4d93a26d54b83533b1475",
   "jinja2_rev": "@2222b31554f03e62600cd7e383376a7c187967a1",
   "json_rpc_2_tag": "@1.1.1",
-  "linter_rev": "@4930ad59a9425300c7dea36281ae09bd682afdb6",
+  "linter_rev": "@afde8f4e2325b234db5c23f99b8386e4f8e10145",
   "logging_rev": "@85d83e002670545e9039ad3985f0018ab640e597",
   "markdown_rev": "@4aaadf3d940bb172e1f6285af4d2b1710d309982",
   "matcher_tag": "@0.12.0",