Revert "[Reland] Block resources in FormStructureBrowserTest."

This reverts commit d15dd85fbe28ee8991802c55314bc97c0ee8a7cf.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [Reland] Block resources in FormStructureBrowserTest.
> 
> The files used for FormStructureBrowserTest are snapshots of real web
> sites. They can have link to online resources but should not need them
> for the test to pass.
> But if the network is really bad, the page can wait for the resource
> loading to finish and timeout.
> Preventing the resource loading will make the test faster and more
> robust.
> 
> Bug: 896173
> Change-Id: I16b02e1d7defd4d950e6ee4cd21bd0133b9ac957
> Reviewed-on: https://chromium-review.googlesource.com/c/1346462
> Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
> Reviewed-by: Eugene But <eugenebut@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#610366}

TBR=eugenebut@chromium.org,olivierrobin@chromium.org

Change-Id: I6628a9daa5b9d5a28b3cd9cda86272fe22dec8c6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 896173
Reviewed-on: https://chromium-review.googlesource.com/c/1347284
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610372}
3 files changed