Temporarily enable network request from newtab

[simonhong]

close brave/brave-browser#272

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions

[emerick]

LGTM

[bridiver]

@simonhong if this is temporary, is there an issue to track the long-term fix?

[simonhong]

@bridiver yep, this - brave/brave-browser#273

[bridiver]

Thanks!