Now that we are using preloaded drawables in compatibilty mode, when
constructing them from their constant state we need to set the new
drawable's target density appropriately.
Change-Id: I3665cbea09d38b9ac5f45f8c380dc8641f86b266
The mColors member can be null, as can be seen in
GradientDrawable.setSolidColor() or the plain constructor. In that case, an NPE
will be thrown on attempts to derive a new GradientDrawable from the instance
using the private constructor GradientDrawable(GradientDrawable).
The problem also occurs when inflating a GradientDrawable from XML without
defining the start, center and end colors and then calling mutate() on the
instance.
