The current logic doesn't account for the special case of `select[multiple]` inputs which lack a single value to synchronize: The value to synchronize is an array of zero or more values.
This change replaces `_getInputStatePropertyName()` with `_getInputState()`, which returns the state for an input depending on its type, and `_setInputState()`, which updates an input's state based on its type.
props westonruter.
fixes#31885.
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