Re-implement the status page for the new task model

pkg/analyzer/lib/src/context/cache.dart

Index: pkg/analyzer/lib/src/context/cache.dart
diff --git a/pkg/analyzer/lib/src/context/cache.dart b/pkg/analyzer/lib/src/context/cache.dart
index 8a21142223521d50b917ee4e7fc051e36f61bccf..b2110673f7f33a1e545291ac664549ae7953ee96 100644
--- a/pkg/analyzer/lib/src/context/cache.dart
+++ b/pkg/analyzer/lib/src/context/cache.dart
@@ -313,6 +313,12 @@ class CacheEntry {
   }
 
   /**
+   * Return a list of result descriptors for results whose state is not
+   * [CacheState.INVALID].
+   */
+  List<ResultDescriptor> get nonInvalidResults => _resultMap.keys.toList();
+
+  /**
    * Fix the state of the [exception] to match the current state of the entry.
    */
   void fixExceptionState() {