[1] define missing observe() section (igrigorik著, ) <https://github.com/w3c/performance-timeline/commit/a61e274e1624ff146b18d52975025a8a1e44e2e2>
[2] move ObserverInit/ObserverEntryList under observe() (igrigorik著, ) <https://github.com/w3c/performance-timeline/commit/43cf7a3255e82a01bcd9df04ada845616407db30>