Remove V8TestSerializedScriptValueInterface.cpp.

The file has been removed as part of r163135 but got merge back again in r163178 by accident.

Lets try to remove it again for good this time.

BUG=270033
NOTRY=true

Review URL: https://codereview.chromium.org/107093008

git-svn-id: svn://svn.chromium.org/blink/trunk@163484 bbb929c8-8fbe-4397-9dbb-9b2b20218538