Code completion improvement. Recommend all 'E.x' where E is an enum, also, filter out only the cor…

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 80b98d8b6e59efb751377834662814a6464c27b3..991ca5f3098e38ed3c4bead367b8f2b2b1346120 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/optype.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/optype.dart
@@ -504,8 +504,7 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
     if (_isEntityPrevTokenSynthetic()) {
       // Actual: if (var v i^)
       // Parsed: if (v) i^;
-    } else if (identical(
-        entity, node.condition)) {
+    } else if (identical(entity, node.condition)) {
       optype.includeReturnValueSuggestions = true;
       optype.includeTypeNameSuggestions = true;
     } else if (identical(entity, node.thenStatement) ||
@@ -622,6 +621,16 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
       optype.includeReturnValueSuggestions = true;
       optype.returnValueSuggestionsFilter = (DartType dartType, int relevance) {
         DartType type = node.element?.type;
+        bool isEnum = type != null &&
+            type.element is ClassElement &&
+            (type.element as ClassElement).isEnum;
+        if (isEnum) {
+          if (type == dartType) {
+            return relevance + DART_RELEVANCE_INCREMENT;
+          } else {
+            return null;
+          }
+        }
         if (type != null &&
             dartType != null &&
             !type.isDynamic &&
@@ -848,8 +857,7 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
 
   bool _isEntityPrevTokenSynthetic() {
     Object entity = this.entity;
-    if (entity is AstNode && entity.beginToken.previous?.isSynthetic ??
-        false) {
+    if (entity is AstNode && entity.beginToken.previous?.isSynthetic ?? false) {
       return true;
     }
     return false;