Don't use .gitignore when determining what to build/serve/run.

sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart

Index: sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart
diff --git a/sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart b/sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart
index 73b40e7f400149744bc845b2b2d8fb5ac6989ea4..10b351fb0563f6d91790b007081f3c0f9a68619e 100644
--- a/sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart
+++ b/sdk/lib/_internal/pub/lib/src/validator/compiled_dartdoc.dart
@@ -20,7 +20,7 @@ class CompiledDartdocValidator extends Validator {
 
   Future validate() {
     return new Future.sync(() {
-      for (var entry in entrypoint.root.listFiles()) {
+      for (var entry in entrypoint.root.listFiles(useGitIgnore: true)) {
         if (path.basename(entry) != "nav.json") continue;
         var dir = path.dirname(entry);