Add AnalysisCache.getState() and getValue().

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 674aeb9b00be5383294caaea7630e6a489b5fc6c..0d56d44ea3d6212bd967243a5104041233951556 100644
--- a/pkg/analyzer/lib/src/task/dart_work_manager.dart
+++ b/pkg/analyzer/lib/src/task/dart_work_manager.dart
@@ -178,8 +178,8 @@ class DartWorkManager implements WorkManager {
    * computing, i.e. it is not in the valid and not in the error state.
    */
   bool _needsComputing(AnalysisTarget target, ResultDescriptor result) {
-    CacheEntry entry = context.getCacheEntry(target);
-    CacheState state = entry.getState(result);
+    AnalysisCache cache = context.analysisCache;
+    CacheState state = cache.getState(target, result);
     return state != CacheState.VALID && state != CacheState.ERROR;
   }
 }