Auto merge of #1991 - glennw:fix-servo-record, r=jrmuizel
Auto merge of #1991 - glennw:fix-servo-record, r=jrmuizel

Ensure that HitTest and GetScrollState are not serialized.

These contain Sender objects that can't be serialized. These
messages are used by Servo and were preventing binary
recordings from working.

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