Autosizing storage doesnot belong on FrameView

    Removing AutoSize storage from Frameview and create seperate struct to handle autoSize

BUG=401254

Review URL: https://codereview.chromium.org/459633002

git-svn-id: svn://svn.chromium.org/blink/trunk@180663 bbb929c8-8fbe-4397-9dbb-9b2b20218538