* array.c (rb_ary_modify): remember shared array owner if a shared
  array owner is promoted and a shared array is not promoted.
  Now, shared array is WB-unprotected so that shared arrays are not
  promoted.  All objects referred from shared array should be marked
  correctly.
  [ruby-core:61919] [ruby-trunk - Bug #9718]
* test/ruby/test_array.rb: add a test for above.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45553 b2dd03c8-39d4-4d8f-98ff-823fe69b080e