Chrome Version: 58.0.3029.19 unknown (64-bit)
OS: Goobuntu (probably all)

What steps will reproduce the problem?
(1) Check out a W3C spec using ReSpec (e.g., https://github.com/w3c/presentation-api)
(2) Go to Chrome settings and block third-party cookies by default.
(3) Try to load the spec's index.html from a file:/// URL on local disk.

What is the expected result?
Spec is rendered normally.

What happens instead?
(4) Page is blank for ~30 seconds and eventually renders.
(5) Cookie blocking icon appears in omnibox and tells me that an IndexedDB on file:/// was blocked for file://.
(6) JS console prints:

Uncaught (in promise) DOMException: The user denied permission to access the database.
<then ReSpec errors about the biblio plugin taking too long>

I can try to construct a narrower repro case if it would be helpful.

I don't know if this is intentional in the behavior for file:/// URLs or not, thus I'm filing this bug.

- With cookie blocking enabled, are file:/// pages allowed a usable storage partition at all?
- Do users expect file:/// URLs to break with third party cookie blocking enabled?