Fix issue of add/remove a frame at a scene before all key frames of a layer. When you added or removed a frame at a scene before all key frames of a layer, frameline was not updated correctly. It seems nothing happened, but domview is updated. This changeset fix this issue by correcting logic for boundary case.

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">testpath</string>
</resources>