Revert "Attempt to fix page-agent-get-resource-tree on the bot"

Didn't actually fix the bot:
http://build.chromium.org/p/client.mojo/builders/Mojo%20Linux/builds/321/steps/mojob%20test/logs/stdio
so there is no point in keeping this change.

This reverts commit 4e50a3cdf887a77adfb0adf5f4e5ebc42a2d99f7.

TBR=ojan@chromium.org

Review URL: https://codereview.chromium.org/742783003