Standardize a word for "strict" in doc/ja
Update translation in doc/ja/core/delete

Adjust to d9aeb54a3fc9e08db17f4dfa62fe045b9bdd3c9d modifying
Improve expression in doc/ja/object/prototype
Improve expression in doc/ja/other/timeouts

Clarify "don't have to" or "must not" in japanese.
I guess origin looks like "must not" than "don't have to".