Filter lists are considered out of date in incognito mode #399

Prerequisites

• [x ] I verified that this is not a filter issue
  • Filter issues MUST be reported at filter issue tracker
• [x ] This is not a support issue or a question
  • Support issues and questions are handled at /r/uBlockOrigin
• [ x] I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
• I tried to reproduce the issue when...
  • [x ] uBlock Origin is the only extension
  • [x ] uBlock Origin with default lists/settings
  • [x ] using a new, unmodified browser profile
• [x ] I am running the latest version of uBlock Origin
• [x ] I checked the documentation to understand that the issue I report is not a normal behavior

Description

Filter lists are always considered out of date if you open a new incognito mode window in Chrome.
Worked fine with 1.17.4

Steps to Reproduce

1. Open a new browser session using Chrome
2. Make sure that all Filter lists are up to date
3. Open a new incognito window
4. Open the Filter lists tab in the dashboard

Expected behavior:

Actual behavior:

Your environment

• uBlock Origin version: 1.18.0
• Browser Name and version: Chrome 71
• Operating System and version: Windows 10