Revert of Fix flaky crash in WebPagePopupImpl::closePopup.

Revert of Fix flaky crash in WebPagePopupImpl::closePopup. (patchset #1 id:1 of https://codereview.chromium.org/1291303002/ )

Reason for revert:
Caused another issue.


Original issue's description:
> Fix flaky crash in WebPagePopupImpl::closePopup.
> 
> Reentrance to WebViewImpl::closePagePopup is possible.  closePopup crashed in
> that case because m_page was valid and m_page->mainFrame() was nullptr.
> 
> The details:
> If WebViewImpl::closePagePopup is called, and the LocalFrame in the page popup
> has the last references to the page popup owner Element,
>  1. WebPagePopupImpl::closePopup() calls destroyPage().
>  2. destroyPage() calls Page::willBeDestroyed().
>  3. willBeDestroyed() destructs the LocalFrame.
>  4. The LocalFrame destructor destructs the owner Element.
>  5. The owner Element destructor destructs PickerIndicatorElement.
>  6. PickerIndicatorElement destructor calls WebViewImpl::closePagePopup().
> 
> This CL changes WebViewImpl::closePagePopup() so that m_pagePopup is cleared
> before calling WebPagePopupImpl::closePopup() to avoid reentrancy to it.
> 
> BUG=454043
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200528

TBR=keishi@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=454043
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200621

[tkent, 2015-08-17 02:21:40]

Created Revert of Fix flaky crash in WebPagePopupImpl::closePopup.

[commit-bot: I haz the power, 2015-08-17 02:21:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1297883002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1297883002/1

[commit-bot: I haz the power, 2015-08-17 02:22:12]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200621