Revert of Make Window.prototype.toString return [object Window] at all times.

Revert of Make Window.prototype.toString return [object Window] at all times. (patchset #4 id:60001 of https://codereview.chromium.org/1138583002/)

Reason for revert:
Going to disable --harmony-tostring until our bindings have been updated.

Original issue's description:
> Make Window.prototype.toString return [object Window] at all times.
> 
> The old code was incorrectly falling back to
> Object.prototype.toString.call which does not work as expected without
> full support for @@toSringTag
> 
> BUG=239915
> R=adamk, jsbell
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=195193

TBR=adamk@chromium.org,jsbell@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=239915
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196348

[arv (Not doing code reviews), 2015-06-02 21:54:39]

Created Revert of Make Window.prototype.toString return [object Window] at all
times.

[commit-bot: I haz the power, 2015-06-02 21:55:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163943002/1

[commit-bot: I haz the power, 2015-06-02 21:56:46]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196348

[adamk, 2015-06-02 21:58:47]

lgtm