gardening: inspector/split-view.html is asserting at RenderFlexibleBox.cpp(624)

BUG=366185
TBR= leviw@chromium.org

Review URL: https://codereview.chromium.org/357373002

git-svn-id: svn://svn.chromium.org/blink/trunk@177277 bbb929c8-8fbe-4397-9dbb-9b2b20218538