GitLab

OfflineAudioContext cannot be closed so it makes more sense to have
close() be defined on AudioContext instead of BaseAudioContext.

This is a very minor tweak to the API, so no Blink intent submitted.

Spec issue: https://github.com/WebAudio/web-audio-api/issues/948
Resolved:   https://github.com/WebAudio/web-audio-api/issues/974
Chrome feature: https://www.chromestatus.com/feature/5683205155848192

BUG=647261
TEST=audiocontext-close.html

Review-Url: https://codereview.chromium.org/2345693002
Cr-Commit-Position: refs/heads/master@{#419244}