Improve name generation for indexed expressions

pkg/analysis_server/test/abstract_context.dart

Index: pkg/analysis_server/test/abstract_context.dart
diff --git a/pkg/analysis_server/test/abstract_context.dart b/pkg/analysis_server/test/abstract_context.dart
index e7dfc1c586964defa2d089b950e79492da9d87d4..44b37a22e469ffa3e57c006d1f3691858294b6eb 100644
--- a/pkg/analysis_server/test/abstract_context.dart
+++ b/pkg/analysis_server/test/abstract_context.dart
@@ -68,8 +68,8 @@ class Required {
 ''');
 
   Source addPackageSource(String packageName, String filePath, String content) {
-    packageMap[packageName] = [(newFolder('/pubcache/$packageName'))];
-    File file = newFile('/pubcache/$packageName/$filePath', content);
+    packageMap[packageName] = [(newFolder('/pubcache/$packageName/lib'))];
+    File file = newFile('/pubcache/$packageName/lib/$filePath', content);
     return file.createSource();
   }