Issue 25622. Quick fix for 'async-for'.

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/fix_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index fa16435cc086168fed1848b55c8c87e69ec507ee..a400a0cd5f0fffd706a15639ab8df5bfab4cf529 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -149,6 +149,9 @@ class FixProcessor {
         CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE) {
       _addFix_replaceWithConstInstanceCreation();
     }
+    if (errorCode == CompileTimeErrorCode.ASYNC_FOR_IN_WRONG_CONTEXT) {
+      bool isAsync = _addFix_addAsync_asyncFor();
+    }
     if (errorCode == CompileTimeErrorCode.INVALID_ANNOTATION) {
       if (node is Annotation) {
         Annotation annotation = node;
@@ -394,6 +397,14 @@ class FixProcessor {
     return false;
   }
 
+  void _addFix_addAsync_asyncFor() {
+    FunctionBody body = node.getAncestor((n) => n is FunctionBody);
+    if (body != null && body.keyword == null) {
+      _addReplaceEdit(rf.rangeStartLength(body, 0), 'async ');
+      _addFix(DartFixKind.ADD_ASYNC, []);
+    }
+  }
+
   void _addFix_addMissingParameter() {
     if (node is ArgumentList && node.parent is MethodInvocation) {
       ArgumentList argumentList = node;