Don't schedule LIBRARY_ERRORS_READY for libraries that should not be analyzed.

pkg/analyzer/lib/src/task/dart_work_manager.dart

Index: pkg/analyzer/lib/src/task/dart_work_manager.dart
diff --git a/pkg/analyzer/lib/src/task/dart_work_manager.dart b/pkg/analyzer/lib/src/task/dart_work_manager.dart
index e006f86e5d0e11c8edf0f157b30d2d9f4c663881..32edf26fea5cb1215fb311dca7ea25e149ec4f42 100644
--- a/pkg/analyzer/lib/src/task/dart_work_manager.dart
+++ b/pkg/analyzer/lib/src/task/dart_work_manager.dart
@@ -12,6 +12,7 @@ import 'package:analyzer/src/generated/engine.dart'
         AnalysisEngine,
         AnalysisErrorInfo,
         AnalysisErrorInfoImpl,
+        AnalysisOptions,
         CacheState,
         InternalAnalysisContext;
 import 'package:analyzer/src/generated/error.dart';
@@ -254,7 +255,8 @@ class DartWorkManager implements WorkManager {
       SourceKind kind = outputs[SOURCE_KIND];
       if (kind != null) {
         unknownSourceQueue.remove(target);
-        if (kind == SourceKind.LIBRARY) {
+        if (kind == SourceKind.LIBRARY &&
+            context.shouldErrorsBeAnalyzed(target, null)) {
           librarySourceQueue.add(target);
         }
       }