add additional lints for the dartdoc codebase (#1374)

Author: devoncarew

.analysis_options renamed to analysis_options.yaml

@@ -10,3 +10,9 @@ analyzer:
 linter:
   rules:
     - annotate_overrides
+    - avoid_init_to_null
+    - directives_ordering
+    - no_adjacent_strings_in_list
+    - package_api_docs
+    - slash_for_doc_comments
+#    - unnecessary_brace_in_string_interps

lib/src/model.dart

@@ -2773,7 +2773,7 @@ class Package implements Nameable, Documentable {
     if (_elementToLibrary.containsKey(element)) {
       return _elementToLibrary[element];
     }
-    Library foundLibrary = null;
+    Library foundLibrary;
     if (libraryElementReexportedBy.containsKey(element.library)) {
       Set<Library> exportedIn = libraryElementReexportedBy[element.library];
       foundLibrary = exportedIn.firstWhere(

test/compare_output_test.dart

@@ -112,8 +112,7 @@ void main() {
 
       message.addAll([
         '',
-        "If there have been changes to generation"
-            " you may need to run `grind update-test-package-docs` again."
+        'If there have been changes to generation you may need to run `grind update-test-package-docs` again.'
       ]);
 
       fail(message.join('\n'));