Version 4.3.61.17 (cherry-pick)

Merged ad854ea1

Allow for accessing an ArrayBuffer contents without externalizing it

TBR=danno@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1111413006

Cr-Commit-Position: refs/branch-heads/4.3@{#20}
Cr-Branched-From: f5c0a23a-refs/heads/4.3.61@{#1}
Cr-Branched-From: 0a7d4f49-refs/heads/master@{#27508}