see devtools issue filed here: https://github.com/ChromeDevTools/devtools-protocol/issues/43
and thread on headless-dev: https://groups.google.com/a/chromium.org/d/msgid/headless-dev/f9a2be5c-2157-43c2-b524-2f8f4c95df29%40chromium.org

Possible repro:

1. Launch Chrome
2. Connect and create a new target with createBrowserContext
3. Connect to that browser context, open a page, set some keys into local storage
4. Repeat Step 2 and then lookup that local-storage key. It shouldn't return a value but does.

Cookie isolation seems not to be affected.