Remove unneeded tests.

Sizes of requests made by NPAPI plugin will never be able in DevTools anymore so these tests are not needed anymore.

TBR=eustas
BUG=233124
NOTRY=true

Review URL: https://codereview.chromium.org/250923013

git-svn-id: svn://svn.chromium.org/blink/trunk@172758 bbb929c8-8fbe-4397-9dbb-9b2b20218538