Chicago-based consumer goods giant Sara Lee Corporation is rolling out a new bread loaf product with no crusts.   Baked and de-crusted at Sara Lee's bakery in Paris, Texas, the IronKids Crustless Bread will be supported by advertising revenue of more than US$10m.   The new crustless bread was formally launched on Sunday at the Food Marketing Institute Show at McCormick Place, and will cost consumers 40 cents more a loaf than the with-crust IronKids equivalent. A spokesman said that "convenience is a very important commodity that parents are willing to pay for".