Workaround for broken SPKAC generated by Chrome

Valid SPKAC asn1parse:

        0:d=0  hl=4 l= 585 cons: SEQUENCE
        4:d=1  hl=4 l= 305 cons:  SEQUENCE
        8:d=2  hl=4 l= 290 cons:   SEQUENCE
       12:d=3  hl=2 l=  13 cons:    SEQUENCE
       14:d=4  hl=2 l=   9 prim:     OBJECT            :rsaEncryption
       25:d=4  hl=2 l=   0 prim:     NULL
       27:d=3  hl=4 l= 271 prim:    BIT STRING
      302:d=2  hl=2 l=   9 prim:   IA5STRING         :challenge
      313:d=1  hl=2 l=  13 cons:  SEQUENCE
      315:d=2  hl=2 l=   9 prim:   OBJECT            :md5WithRSAEncryption
      326:d=2  hl=2 l=   0 prim:   NULL
      328:d=1  hl=4 l= 257 prim:  BIT STRING

Offending SPKAC generated by Chrome:

        0:d=0  hl=4 l= 572 cons: SEQUENCE
        4:d=1  hl=4 l= 294 cons:  SEQUENCE
        8:d=2  hl=4 l= 288 cons:   SEQUENCE
       12:d=3  hl=2 l=  11 cons:    SEQUENCE
       14:d=4  hl=2 l=   9 prim:     OBJECT            :rsaEncryption
       25:d=3  hl=4 l= 271 prim:    BIT STRING
      300:d=2  hl=2 l=   0 prim:   IA5STRING         :
      302:d=1  hl=2 l=  11 cons:  SEQUENCE
      304:d=2  hl=2 l=   9 prim:   OBJECT            :md5WithRSAEncryption
      315:d=1  hl=4 l= 257 prim:  BIT STRING