jb v8 debug protocol: load full string value

(cherry picked from commit 014c0e336b7d666875621aef3d847cbaf4ee780c)
use provided value description instead of just classname
don't compute object presentation by custom configured properties if value description is not equals to class name

(cherry picked from commit 76fcb91426c4b9bc4fb1743bc0aa30e20dd4016c)