Sometimes the protocol buffer data (RiceEncodingData) sent by Google's Safe Browsing server has the following properties:
1. |has_first_value| is false
2. |num_entries| > 0
In this case, we can still parse the data and apply partial update correctly by assuming that the first value is equal to 0.
Differential Revision: https://phabricator.services.mozilla.com/D6393
16c28822da