Refactoring of ScriptValueSerializer::doSerializeObject()

      This CL does following changes
- Rename 'jsObject' as 'object'
- Reorder type checks
- Merge some 'if' branches which check conditions
- Unify write{Transferred}XXX methods

BUG=148757

Review-Url: https://codereview.chromium.org/1998053002
Cr-Commit-Position: refs/heads/master@{#395329}