This is more consistent with the DOM API, and is clearer w.r.t. which values
are available in the lexical environment of the Worker.
BUG=chromium:497295
R=jarin@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1218553004
Cr-Commit-Position: refs/heads/master@{#29426}
v8::Internal::List will DCHECK when indexing out of the array, even if just to
get the address, and the value is never used. So this construct will fail:
memcpy(p, &data[0], length);
When data is empty and length is 0.
BUG=chromium:505778
R=mstarzinger@chromium.org
LOG=n
Review URL: https://codereview.chromium.org/1216853003
Cr-Commit-Position: refs/heads/master@{#29388}