Unexpected displaying the ask dialog when close the 'Preferences' form

[artaleks9]

Description

Reproduction Steps:

• Open the IDE and click Profile -> Preferences -> Contribute (as example)
• The Save button is disabled
• Change the state of the checkbox (the Save button becomes enabled)
• Click on the Refresh button, the Save button changes to disabled
• Close the Preferences form

Expected behavior:

• the Preferences form should be closed

Observed behavior:

• the ask dialog is displayed with a propose to save changes

Che version: 6.7.0
OS and version: Fedora 28
Che install: Docker/OCP
Docker version: 17.09
API docker version: 1.32

Additional information:

• Related issue: Wrong behavior the 'Save' button in the 'Preferences'  #9959
• Related selenium tests: ContributeTabTest
• Problem can be reliably reproduced, doesn't happen randomly: [No]
• See the attachment: