[License] Enable always_require_non_null_named_parameters

Adds dependency on package:meta.

ci/licenses_golden/tool_signature

@@ -1,2 +1,2 @@
-Signature: 0461a8d6fe3503cd19d8e0d3becfee87
+Signature: acd8a02ea76b205ea2dbea4c91961320
 

tools/licenses/analysis_options.yaml

@@ -10,6 +10,7 @@ analyzer:
 
 linter:
   rules:
+    - always_require_non_null_named_parameters
     - avoid_empty_else
     - avoid_function_literals_in_foreach_calls
     - comment_references

tools/licenses/lib/licenses.dart

@@ -5,6 +5,8 @@
 import 'dart:convert';
 import 'dart:io' as system;
 
+import 'package:meta/meta.dart';
+
 import 'cache.dart';
 import 'limits.dart';
 import 'patterns.dart';
@@ -838,7 +840,10 @@ Iterable<_LicenseMatch> _tryReferenceByUrl(String body, MultipleVersionedLicense
   }
 }
 
-Iterable<_LicenseMatch> _tryInline(String body, RegExp pattern, { bool needsCopyright, String origin }) sync* {
+Iterable<_LicenseMatch> _tryInline(String body, RegExp pattern, {
+  @required bool needsCopyright,
+  String origin,
+}) sync* {
   assert(needsCopyright != null);
   for (_PartialLicenseMatch match in _findLicenseBlocks(body, pattern, 1, 2, needsCopyright: false)) {
     // We search with "needsCopyright: false" but then create a _LicenseMatch with

tools/licenses/pubspec.yaml

@@ -1,6 +1,7 @@
 name: licenses
 dependencies:
-  path: ^1.3.0
   archive: ^2.0.4
   args: 1.5.0
   crypto: ^2.0.2+1
+  meta: ^1.1.6
+  path: ^1.3.0