Deserialized extension block menus always select default

[cwillisf]

Expected Behavior

Saving (serializing) a project, then loading it (deserializing) again, should result in the same values in all blocks in the project.

Actual Behavior

Any extension block containing a drop-down menu resets to the default value for that dropdown.

Steps to Reproduce

1. Load project 105661210 in both Scratch 2.0 and 3.0, in different windows or tabs
2. Compare the values of the drop-down menus in these blocks:

• "tilt angle {}" block
• "turn {} on for {} secs" block
• "set {} direction to {}"