Reorganize InheritedRefenenceContributor to serve angular completion

pkg/analysis_server/lib/src/services/completion/dart/optype.dart

Index: pkg/analysis_server/lib/src/services/completion/dart/optype.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/optype.dart b/pkg/analysis_server/lib/src/services/completion/dart/optype.dart
index 0591ae2c28679e1453025b223c5c99d5bf8acb9e..da0e6a03ef924391f368ac76c93b13d8bb24bead 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/optype.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/optype.dart
@@ -135,6 +135,17 @@ class OpType {
       !includeVoidReturnSuggestions;
 
   /**
+   * Return `true` if free standing identifiers should be suggested
+   */
+  bool get includeIdentifiers {
+    return !isPrefixed &&
+        (includeReturnValueSuggestions ||
+            includeTypeNameSuggestions ||
+            includeVoidReturnSuggestions ||
+            includeConstructorSuggestions);
+  }
+
+  /**
    * Indicate whether only type names should be suggested
    */
   bool get includeOnlyTypeNameSuggestions =>