Issue 54362. Allow importing lower case named types.

Bug: #54362
Change-Id: I59359262bee28eb55d2e0220750f1d7628293d96
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/356661
Reviewed-by: Keerti Parthasarathy <keertip@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

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

@@ -150,18 +150,17 @@ class ImportLibrary extends MultiCorrectionProducer {
   @override
   String? nameOfType(AstNode node) {
     final parent = node.parent;
-    if (node is NamedType) {
-      final importPrefix = node.importPrefix;
-      if (parent is ConstructorName && importPrefix != null) {
-        return importPrefix.name.lexeme;
-      }
-      return node.name2.lexeme;
-    } else if (node is PrefixedIdentifier) {
-      if (parent is NamedType) {
-        return node.prefix.name;
-      }
+    switch (node) {
+      case NamedType():
+        final importPrefix = node.importPrefix;
+        if (parent is ConstructorName && importPrefix != null) {
+          return importPrefix.name.lexeme;
+        }
+        return node.name2.lexeme;
+      case SimpleIdentifier():
+        return node.name;
     }
-    return super.nameOfType(node);
+    return null;
   }
 
   void _importExtensionInLibrary(

pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart

@@ -963,6 +963,24 @@ void f(Test t) {}
 ''', target: b.path);
   }
 
+  Future<void> test_withClass_simpleIdentifier_lowerCase() async {
+    newFile('$testPackageLibPath/lib.dart', '''
+class eX {}
+''');
+    await resolveTestCode('''
+void f() {
+  eX;
+}
+''');
+    await assertHasFix('''
+import 'package:test/lib.dart';
+
+void f() {
+  eX;
+}
+''');
+  }
+
   Future<void> test_withExtension_pub_this() async {
     updateTestPubspecFile(r'''
 name: test