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

pkg/analyzer/test/generated/engine_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.engine_test;
 
 import 'dart:async';
@@ skipping 5780 matching lines @@
       int oldLength, int newLength) {
     fail("Unexpected invocation of setChangedContents");
   }
 
   @override
   void setContents(Source source, String contents) {
     fail("Unexpected invocation of setContents");
   }
 
   @override
+  bool shouldErrorsBeAnalyzed(Source source, Object entry) {
+    fail("Unexpected invocation of shouldErrorsBeAnalyzed");
+    return false;
+  }
+  @override
   void visitCacheItems(void callback(Source source, SourceEntry dartEntry,
       DataDescriptor rowDesc, CacheState state)) {
     fail("Unexpected invocation of visitCacheItems");
   }
 }
 
 class TestAnalysisContext_test_applyChanges extends TestAnalysisContext {
   bool invoked = false;
   TestAnalysisContext_test_applyChanges();
   @override
@@ skipping 791 matching lines @@
   @override
   bool exists() => true;
 }
 
 class _UniversalCachePartitionTest_test_setMaxCacheSize
     implements CacheRetentionPolicy {
   @override
   RetentionPriority getAstPriority(Source source, SourceEntry sourceEntry) =>
       RetentionPriority.LOW;
 }