Revert of Change Event.deepPath to a method (patchset #4 id:60001 of https://codereview.chromium.org/1637813002/ )

Reason for revert:
Breaks devtools. Landed without devtools review.

Original issue's description:
> Change Event.deepPath to a method
>
> In order to make clear that computation is performed, Event.deepPath has been changed to a method Event.deepPath(), that returns sequence<EventTarget>.
> See the discussion here: https://github.com/w3c/webcomponents/issues/361
> Described in the spec here : http://w3c.github.io/webcomponents/spec/shadow/#widl-Event-deepPath-sequence-EventTarget
> See the spec change here: https://github.com/w3c/webcomponents/commit/ed93413f9a37a6bfbd774cb2e09e14a76c87d56c
> BUG=531990
>
> Committed: https://crrev.com/b9279be7d61887c171d5c1cefa114292c84b9957
> Cr-Commit-Position: refs/heads/master@{#372596}
>
> Committed: https://crrev.com/074da65f2d82b187dc44c5c5be09d3fec100d63d
> Cr-Commit-Position: refs/heads/master@{#376103}

TBR=samli@chromium.org,hayato@chromium.org,kochi@chromium.org,kojii@chromium.org,yuzus@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=531990

Review URL: https://codereview.chromium.org/1710893003

Cr-Commit-Position: refs/heads/master@{#376223}
8 files changed