Refactor: unsigned short -> uint8_t in third_party/blink/renderer/modules/webaudio

- unsigned short -> uint8_t.
- No logic changes.
- Reference: https://google.github.io/styleguide/cppguide.html#Integer_Types

Bug: 929986
Change-Id: I854a58dada8ad3a7b5334239e85fb450e2053c0e
Reviewed-on: https://chromium-review.googlesource.com/c/1478314
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Miyoung Shin <myid.shin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633663}
2 files changed