Layout: Fix resize (which just plain doesn't work right now).

Currently, both restyle/flow construction _and_ reflow are skipped
during resize. Reflow should not be in that list. This patch fixes
that.
combine conditions
remove warning
auto merge of #3826 : cgaebel/servo/fix-resize, r=pcwalton

Currently, both restyle/flow construction _and_ reflow are skipped
during resize. Reflow should not be in that list. This patch fixes
that.