ECKey.decodeFromDER(): Also throws IllegalArgumentException if unexpected class was read.
ECKey.decodeFromDER(): Also throws IllegalArgumentException if unexpected class was read.

Fixes a regression that was introduced with commit e5f14e789a391bb1ed89e78943a25eed12943334.

(cherry picked from commit 3ef5f9f2d7b4ef911af5813c58a43817d3bf399e)

HashEngineering/dashj,HashEngineering/darkcoinj,HashEngineering/darkcoinj,HashEngineering/dashj,HashEngineering/dashj,HashEngineering/dashj,HashEngineering/darkcoinj