Delete PerformanceTests/inspector/native-memory-snapshot.html

Native memory instrumentaton has been removed. The test should also be removed.

BUG=234422
R=alph@chromium.org

Review URL: https://codereview.chromium.org/19755002

git-svn-id: svn://svn.chromium.org/blink/trunk@154482 bbb929c8-8fbe-4397-9dbb-9b2b20218538