Update subclasses array and is_implemented bit when loading script snapshots.

runtime/vm/snapshot_test.cc

Index: runtime/vm/snapshot_test.cc
diff --git a/runtime/vm/snapshot_test.cc b/runtime/vm/snapshot_test.cc
index 510e1eb5d7084bf8ca26fedca1ed149fdbcc469d..72e54f8065b4581c7b09bb8860f6f0cd59463621 100644
--- a/runtime/vm/snapshot_test.cc
+++ b/runtime/vm/snapshot_test.cc
@@ -1002,7 +1002,7 @@ TEST_CASE(SerializeScript) {
 }
 
 
-#if !defined(PRODUCT)  // Uses deferred loading.
+#if !defined(PRODUCT)  // Uses mirrors.
 VM_UNIT_TEST_CASE(CanonicalizationInScriptSnapshots) {
   const char* kScriptChars =
       "\n"
@@ -1109,6 +1109,120 @@ VM_UNIT_TEST_CASE(CanonicalizationInScriptSnapshots) {
 #endif
 
 
+VM_UNIT_TEST_CASE(ScriptSnapshotsUpdateSubclasses) {
+  const char* kScriptChars =
+      "class _DebugDuration extends Duration {\n"
+      "  const _DebugDuration() : super(milliseconds: 42);\n"
+      "}\n"
+      "foo(x, y) {\n"
+      "  for (var i = 0; i < 1000000; i++) {\n"
+      "    if (x != y) {\n"
+      "      throw 'Boom!';\n"
+      "    }\n"
+      "  }\n"
+      "}\n"
+      "main() {\n"
+      "  final v = const Duration(milliseconds: 42);\n"
+      "  foo(v, new _DebugDuration());\n"
+      "}\n"
+      "\n";
+
+  Dart_Handle result;
+
+  uint8_t* buffer;
+  intptr_t size;
+  intptr_t vm_isolate_snapshot_size;
+  uint8_t* isolate_snapshot = NULL;
+  intptr_t isolate_snapshot_size;
+  uint8_t* full_snapshot = NULL;
+  uint8_t* script_snapshot = NULL;
+
+#if !defined(PRODUCT)
+  bool saved_load_deferred_eagerly_mode = FLAG_load_deferred_eagerly;
+  FLAG_load_deferred_eagerly = true;
+#endif
+  intptr_t saved_max_polymorphic_checks = FLAG_max_polymorphic_checks;
+  FLAG_max_polymorphic_checks = 0;
+
+  {
+    // Start an Isolate, and create a full snapshot of it.
+    TestIsolateScope __test_isolate__;
+    Dart_EnterScope();  // Start a Dart API scope for invoking API functions.
+
+    // Write out the script snapshot.
+    result = Dart_CreateSnapshot(NULL, &vm_isolate_snapshot_size,
+                                 &isolate_snapshot, &isolate_snapshot_size);
+    EXPECT_VALID(result);
+    full_snapshot = reinterpret_cast<uint8_t*>(malloc(isolate_snapshot_size));
+    memmove(full_snapshot, isolate_snapshot, isolate_snapshot_size);
+    Dart_ExitScope();
+  }
+
+  {
+    // Now Create an Isolate using the full snapshot and load the
+    // script  and execute it.
+    TestCase::CreateTestIsolateFromSnapshot(full_snapshot);
+    Dart_EnterScope();  // Start a Dart API scope for invoking API functions.
+
+    // Create a test library and Load up a test script in it.
+    Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
+
+    EXPECT_VALID(lib);
+
+    // Invoke a function which returns an object.
+    result = Dart_Invoke(lib, NewString("main"), 0, NULL);
+    EXPECT_VALID(result);
+    Dart_ExitScope();
+    Dart_ShutdownIsolate();
+  }
+
+  {
+    // Create an Isolate using the full snapshot, load a script and create
+    // a script snapshot of the script.
+    TestCase::CreateTestIsolateFromSnapshot(full_snapshot);
+    Dart_EnterScope();  // Start a Dart API scope for invoking API functions.
+
+    // Create a test library and Load up a test script in it.
+    TestCase::LoadTestScript(kScriptChars, NULL);
+
+    EXPECT_VALID(Api::CheckAndFinalizePendingClasses(Thread::Current()));
+
+    // Write out the script snapshot.
+    result = Dart_CreateScriptSnapshot(&buffer, &size);
+    EXPECT_VALID(result);
+    script_snapshot = reinterpret_cast<uint8_t*>(malloc(size));
+    memmove(script_snapshot, buffer, size);
+    Dart_ExitScope();
+    Dart_ShutdownIsolate();
+  }
+
+  {
+    // Now Create an Isolate using the full snapshot and load the
+    // script snapshot created above and execute it.
+    TestCase::CreateTestIsolateFromSnapshot(full_snapshot);
+    Dart_EnterScope();  // Start a Dart API scope for invoking API functions.
+
+    // Load the test library from the snapshot.
+    EXPECT(script_snapshot != NULL);
+    result = Dart_LoadScriptFromSnapshot(script_snapshot, size);
+    EXPECT_VALID(result);
+
+    // Invoke a function which returns an object.
+    result = Dart_Invoke(result, NewString("main"), 0, NULL);
+    EXPECT_VALID(result);
+    Dart_ExitScope();
+    Dart_ShutdownIsolate();
+  }
+  free(script_snapshot);
+  free(full_snapshot);
+
+  FLAG_max_polymorphic_checks = saved_max_polymorphic_checks;
+#if !defined(PRODUCT)
+  FLAG_load_deferred_eagerly = saved_load_deferred_eagerly_mode;
+#endif
+}
+
+
 static void IterateScripts(const Library& lib) {
   const Array& lib_scripts = Array::Handle(lib.LoadedScripts());
   Script& script = Script::Handle();