Add missing backref collection when reading mint and bigint objects in a native message handler

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 b24fe317c0636187c77f01ea17ce4ac4688b5099..0bafa2fd7b6bc188d55f5b4e42fb676fbaea619e 100644
--- a/runtime/vm/snapshot_test.cc
+++ b/runtime/vm/snapshot_test.cc
@@ -1305,6 +1305,18 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
       "  for (var i = 0; i < kArrayLength; i++) list[i] = s;\n"
       "  return list;\n"
       "}\n"
+      "getMintList() {\n"
+      "  var mint = 0x7FFFFFFFFFFFFFFF;\n"
+      "  var list = new List(kArrayLength);\n"
+      "  for (var i = 0; i < kArrayLength; i++) list[i] = mint;\n"
+      "  return list;\n"
+      "}\n"
+      "getBigintList() {\n"
+      "  var bigint = 0x1234567890123456789012345678901234567890;\n"
+      "  var list = new List(kArrayLength);\n"
+      "  for (var i = 0; i < kArrayLength; i++) list[i] = bigint;\n"
+      "  return list;\n"
+      "}\n"
       "getDoubleList() {\n"
       "  var d = 3.14;\n"
       "  var list = new List<double>(kArrayLength);\n"
@@ -1358,6 +1370,32 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
       }
     }
     {
+      // Generate a list of medium ints from Dart code.
+      ApiNativeScope scope;
+      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMintList");
+      EXPECT_NOTNULL(root);
+      EXPECT_EQ(Dart_CObject::kArray, root->type);
+      EXPECT_EQ(kArrayLength, root->value.as_array.length);
+      for (int i = 0; i < kArrayLength; i++) {
+        Dart_CObject* element = root->value.as_array.values[i];
+        EXPECT_EQ(root->value.as_array.values[0], element);
+        EXPECT_EQ(Dart_CObject::kInt64, element->type);
+      }
+    }
+    {
+      // Generate a list of bigints from Dart code.
+      ApiNativeScope scope;
+      Dart_CObject* root = GetDeserializedDartMessage(lib, "getBigintList");
+      EXPECT_NOTNULL(root);
+      EXPECT_EQ(Dart_CObject::kArray, root->type);
+      EXPECT_EQ(kArrayLength, root->value.as_array.length);
+      for (int i = 0; i < kArrayLength; i++) {
+        Dart_CObject* element = root->value.as_array.values[i];
+        EXPECT_EQ(root->value.as_array.values[0], element);
+        EXPECT_EQ(Dart_CObject::kBigint, element->type);
+      }
+    }
+    {
       // Generate a list of doubles from Dart code.
       ApiNativeScope scope;
       Dart_CObject* root = GetDeserializedDartMessage(lib, "getDoubleList");