Revert of Change Event.deepPath to a method (patchset #3 id:40001 of https://codereview.chromium.org/1637813002/ )

Reason for revert:
This breaks new DevTools frontend while remote debugging old backends.

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: WICG/webcomponents#361
> Described in the spec here : http://w3c.github.io/webcomponents/spec/shadow/#widl-Event-deepPath-sequence-EventTarget
> See the spec change here: WICG/webcomponents@ed93413
> BUG=531990
>
> Committed: https://crrev.com/b9279be7d61887c171d5c1cefa114292c84b9957
> Cr-Commit-Position: refs/heads/master@{#372596}

[email protected],[email protected],[email protected],[email protected],[email protected]
# 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/1651193003

Cr-Commit-Position: refs/heads/master@{#372713}

Author: alexkozy

front_end/ui/Tooltip.js

@@ -33,7 +33,7 @@ WebInspector.Tooltip.prototype = {
      */
     _mouseMove: function(event)
     {
-        var path = event.deepPath() ? event.deepPath() : event.path;
+        var path = event.deepPath ? event.deepPath : event.path;
         if (!path || event.buttons !== 0)
             return;