Mix VARIABLE_REFERENCE_ERRORS into the full errors list on ChangeNotice.

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 0654e3c6bcc757819dc4c17a5409f48de877e651..6e7ba5b50ad74a02732252d74f1254861d8f1cdc 100644
--- a/pkg/analyzer/lib/src/task/dart_work_manager.dart
+++ b/pkg/analyzer/lib/src/task/dart_work_manager.dart
@@ -46,6 +46,7 @@ class DartWorkManager implements WorkManager {
     HINTS,
     RESOLVE_REFERENCES_ERRORS,
     RESOLVE_TYPE_NAMES_ERRORS,
+    VARIABLE_REFERENCE_ERRORS,
     VERIFY_ERRORS
   ];
 
@@ -179,6 +180,11 @@ class DartWorkManager implements WorkManager {
    * errors in the source. The errors contained in the list can be incomplete.
    */
   AnalysisErrorInfo getErrors(Source source) {
+    if (analysisCache.getState(source, DART_ERRORS) == CacheState.VALID) {
+      List<AnalysisError> errors = analysisCache.getValue(source, DART_ERRORS);
+      LineInfo lineInfo = analysisCache.getValue(source, LINE_INFO);
+      return new AnalysisErrorInfoImpl(errors, lineInfo);
+    }
     List<AnalysisError> errors = <AnalysisError>[];
     for (ResultDescriptor descriptor in _SOURCE_ERRORS) {
       errors.addAll(analysisCache.getValue(source, descriptor));