simulateExternalChange method
Applies entries and notifies stream listeners - what a write from
another engine or native code looks like to this isolate.
Implementation
void simulateExternalChange(List<StorageEntry> entries) {
for (final entry in entries) {
if (entry.value.isEmpty) {
data.remove(entry.key);
} else {
data[entry.key] = entry.value;
}
}
_controller.add(entries);
}