Replaced elements avoid floats, including check boxes and radio boxes.

Check boxes and radio boxes are the odd man out among form control
elements: they neither have their own renderer class with which to
override avoidFloats nor are they isReplaced(). If the case for
making form control elements isReplaced() builds further than it may
be worth looking at including them in that effort but for now just
replaced the isReplaced() check in avoidsFloats() with a more inclusive
alternative.

BUG=322093

Review URL: https://codereview.chromium.org/296153006

git-svn-id: svn://svn.chromium.org/blink/trunk@178201 bbb929c8-8fbe-4397-9dbb-9b2b20218538