[ios] Fixed dialogs suppression.

[ios] Fixed dialogs suppression.

The issue happened in the following scenario:
 - uer typed in the omnibox to trigger preload
 - preload Tab set shouldSuppressDialogs to YES
 - web view did not exist so suppression was postponed until the load
 - user tapped Go to promote preload Tab to real Tab
 - preload Tab set shouldSuppressDialogs to NO
 - page loaded and postponed suppression suppresses the dialods

This change always cancels postoned suppression if
shouldSuppressDialogs was set to NO.

BUG=618831
Review-Url: https://codereview.chromium.org/2072553002
Cr-Commit-Position: refs/heads/master@{#400020}
(cherry picked from commit fc51dd2482615bab3c156bcd5d3744d146be84ee)

Committed: https://chromium.googlesource.com/chromium/src/+/c37a95a7b5945958ab7eb31464bc2b6599706a5e

[Eugene But (OOO till 7-30), 2016-06-16 21:47:13]

Description was changed from

==========
[ios] Fixed dialogs suppression.

The issue happened in the following scenario:
 - uer typed in the omnibox to trigger preload
 - preload Tab set shouldSuppressDialogs to YES
 - web view did not exist so suppression was postponed until the load
 - user tapped Go to promote preload Tab to real Tab
 - preload Tab set shouldSuppressDialogs to NO
 - page loaded and postponed suppression suppresses the dialods

This change always cancels postoned suppression if
shouldSuppressDialogs was set to NO.

BUG=618831

Review-Url: https://codereview.chromium.org/2072553002
Cr-Commit-Position: refs/heads/master@{#400020}
(cherry picked from commit fc51dd2482615bab3c156bcd5d3744d146be84ee)
==========

to

==========
[ios] Fixed dialogs suppression.

The issue happened in the following scenario:
 - uer typed in the omnibox to trigger preload
 - preload Tab set shouldSuppressDialogs to YES
 - web view did not exist so suppression was postponed until the load
 - user tapped Go to promote preload Tab to real Tab
 - preload Tab set shouldSuppressDialogs to NO
 - page loaded and postponed suppression suppresses the dialods

This change always cancels postoned suppression if
shouldSuppressDialogs was set to NO.

BUG=618831

Review-Url: https://codereview.chromium.org/2072553002
Cr-Commit-Position: refs/heads/master@{#400020}
(cherry picked from commit fc51dd2482615bab3c156bcd5d3744d146be84ee)

Committed:
https://chromium.googlesource.com/chromium/src/+/c37a95a7b5945958ab7eb31464bc...
==========

[Eugene But (OOO till 7-30), 2016-06-16 21:47:15]

Committed patchset #1 (id:1) manually as
c37a95a7b5945958ab7eb31464bc2b6599706a5e.