linter 1.18.0

Change-Id: I227f1994a664a116c5ffdd5a081a6430b2908eaf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/226481
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>

CHANGELOG.md

@@ -63,7 +63,16 @@ in 2018, as it doesn't work with any Dart 2.x release.
 
 #### Linter
 
-Updated the Linter to `1.17.1`, which includes changes that
+Updated the Linter to `1.18.0`, which includes changes that
+
+- extends `camel_case_types` to cover enums.
+- fixes `no_leading_underscores_for_local_identifiers` to not 
+  mis-flag field formal parameters with default values.
+- fixes `prefer_function_declarations_over_variables` to not
+  mis-flag non-final fields.
+- improves performance for `prefer_contains`.
+- updates `exhaustive_cases` to skip deprecated values that
+  redirect to other values.
 - adds new lint: `unnecessary_late`.
 - improves docs for `prefer_initializing_formals`.
 - updates `secure_pubspec_urls` to check `issue_tracker` and

DEPS

@@ -124,7 +124,7 @@ vars = {
   "intl_tag": "0.17.0-nullsafety",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",
   "json_rpc_2_rev": "7e00f893440a72de0637970325e4ea44bd1e8c8e",
-  "linter_tag": "1.17.1",
+  "linter_tag": "1.18.0",
   "lints_tag": "f9670df2a66e0ec12eb51554e70c1cbf56c8f5d0",
   "logging_rev": "575781ef196e4fed4fb737e38fb4b73d62727187",
   "markupsafe_rev": "8f45f5cfa0009d2a70589bcda0349b8cb2b72783",