Revert "[vm/extensions] Fix Loader::ReloadNativeExtensions(...)."

This reverts commit 4118d3c793734e3f5ca500b7aeedf9e4c70d4f62.

Crashes on hot reload/rollback bots.

Original change's description:
> [vm/extensions] Fix Loader::ReloadNativeExtensions(...).
> 
> This method was not doing anything since the switch to Dart 2
> because extensions no longer were added as imports to the libraries
> which loaded them.
> 
> This is a commandeer of https://dart-review.googlesource.com/c/sdk/+/90240 with a bug fix.
> 
> Change-Id: Idfe2ec16ae714b5a31ed53332da6704248949915
> Reviewed-on: https://dart-review.googlesource.com/c/92180
> Commit-Queue: Samir Jindel <sjindel@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>

TBR=rmacnak@google.com,sjindel@google.com

Change-Id: If8c8d6cf8ee2cb0a354601f94c609d3d7b5ddf03
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/92640
Reviewed-by: Samir Jindel <sjindel@google.com>
diff --git a/runtime/vm/kernel_loader.cc b/runtime/vm/kernel_loader.cc
index 2e024aa..690c632 100644
--- a/runtime/vm/kernel_loader.cc
+++ b/runtime/vm/kernel_loader.cc
@@ -614,15 +614,6 @@
       if (result.IsError()) {
         H.ReportError(Error::Cast(result), "library handler failed");
       }
-
-      // Create a dummy library and add it as an import to the current library.
-      // This allows later to discover and reload this native extension, e.g.
-      // when running from an app-jit snapshot.
-      // See Loader::ReloadNativeExtensions(...) which relies on
-      // Dart_GetImportsOfScheme('dart-ext').
-      const auto& native_library = Library::Handle(Library::New(uri_path));
-      library.AddImport(Namespace::Handle(Namespace::New(
-          native_library, Array::null_array(), Array::null_array())));
     }
   }
   potential_extension_libraries_ = GrowableObjectArray::null();
diff --git a/samples/sample_extension/sample_asynchronous_extension.dart b/samples/sample_extension/sample_asynchronous_extension.dart
index 6b81369..69af1e5 100644
--- a/samples/sample_extension/sample_asynchronous_extension.dart
+++ b/samples/sample_extension/sample_asynchronous_extension.dart
@@ -13,7 +13,7 @@
   static SendPort _port;
 
   Future<List<int>> randomArray(int seed, int length) {
-    var completer = new Completer<List<int>>();
+    var completer = new Completer();
     var replyPort = new RawReceivePort();
     var args = new List(3);
     args[0] = seed;
diff --git a/samples/samples.status b/samples/samples.status
index 9ec1b23e..3af1d7e 100644
--- a/samples/samples.status
+++ b/samples/samples.status
@@ -8,6 +8,9 @@
 [ $builder_tag == optimization_counter_threshold ]
 sample_extension/test/sample_extension_app_snapshot_test: SkipByDesign # This test is too slow for testing with low optimization counter threshold.
 
+[ $compiler == app_jit ]
+sample_extension/test/sample_extension_app_snapshot_test: RuntimeError
+
 [ $compiler == precompiler ]
 sample_extension/test/*: Skip # These tests attempt to spawn another script using the precompiled runtime.
 
@@ -23,9 +26,9 @@
 [ !$preview_dart_2 && ($runtime == dart_precompiled || $runtime == vm) ]
 *: SkipByDesign # Deprecating all Dart1 modes of execution
 
-[ $compiler == app_jitk || $compiler == dartkb || $compiler == dartkp ]
-sample_extension/test/sample_extension_app_snapshot_test: SkipByDesign
-sample_extension/test/sample_extension_test: SkipByDesign
+[ $compiler == app_jitk || $compiler == dartk || $compiler == dartkb || $compiler == dartkp ]
+sample_extension/test/sample_extension_app_snapshot_test: RuntimeError
+sample_extension/test/sample_extension_test: RuntimeError
 
 # Skip tests that use dart:io
 [ $runtime == d8 || $browser ]