[tests] Fix use-after-scope errors related to weak refs

BUG=v8:5887

Review-Url: https://codereview.chromium.org/2655533004
Cr-Commit-Position: refs/heads/master@{#42652}

test/cctest/test-api.cc

@@ -7570,13 +7570,14 @@ void InternalFieldCallback(bool global_gc) {
   Trivial* t1;
   Trivial2* t2;
   instance_templ->SetInternalFieldCount(2);
+  v8::Persistent<v8::Object> handle;
   {
     v8::HandleScope scope(isolate);
     Local<v8::Object> obj = templ->GetFunction(env.local())
                                 .ToLocalChecked()
                                 ->NewInstance(env.local())
                                 .ToLocalChecked();
-    v8::Persistent<v8::Object> handle(isolate, obj);
+    handle.Reset(isolate, obj);
     CHECK_EQ(2, obj->InternalFieldCount());
     CHECK(obj->GetInternalField(0)->IsUndefined());
     t1 = new Trivial(42);

test/cctest/test-weakmaps.cc

@@ -111,13 +111,10 @@ TEST(Weakness) {
       0, ObjectHashTable::cast(weakmap->table())->NumberOfDeletedElements());
 
   // Make the global reference to the key weak.
-  {
-    HandleScope scope(isolate);
-    std::pair<Handle<Object>*, int> handle_and_id(&key, 1234);
-    GlobalHandles::MakeWeak(
-        key.location(), reinterpret_cast<void*>(&handle_and_id),
-        &WeakPointerCallback, v8::WeakCallbackType::kParameter);
-  }
+  std::pair<Handle<Object>*, int> handle_and_id(&key, 1234);
+  GlobalHandles::MakeWeak(
+      key.location(), reinterpret_cast<void*>(&handle_and_id),
+      &WeakPointerCallback, v8::WeakCallbackType::kParameter);
   CHECK(global_handles->IsWeak(key.location()));
 
   CcTest::CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);

test/cctest/test-weaksets.cc

@@ -110,13 +110,10 @@ TEST(WeakSet_Weakness) {
       0, ObjectHashTable::cast(weakset->table())->NumberOfDeletedElements());
 
   // Make the global reference to the key weak.
-  {
-    HandleScope scope(isolate);
-    std::pair<Handle<Object>*, int> handle_and_id(&key, 1234);
-    GlobalHandles::MakeWeak(
-        key.location(), reinterpret_cast<void*>(&handle_and_id),
-        &WeakPointerCallback, v8::WeakCallbackType::kParameter);
-  }
+  std::pair<Handle<Object>*, int> handle_and_id(&key, 1234);
+  GlobalHandles::MakeWeak(
+      key.location(), reinterpret_cast<void*>(&handle_and_id),
+      &WeakPointerCallback, v8::WeakCallbackType::kParameter);
   CHECK(global_handles->IsWeak(key.location()));
 
   CcTest::CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);