Mark http/tests/inspector/resource-tree/resource-tree-reload.html as flaky

BUG=328112
TBR=junov@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/102253003

git-svn-id: svn://svn.chromium.org/blink/trunk@163804 bbb929c8-8fbe-4397-9dbb-9b2b20218538