merge revision(s) 40021,42380: [Backport #8686]

	test_method.rb: split

	* test/ruby/test_method.rb (test_define_method): split for each tests.
	* object.c (rb_class_inherited_p): allow iclasses to be tested for
	  inheritance. [Bug #8686] [ruby-core:56174]

	* test/ruby/test_method.rb: add test


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@42914 b2dd03c8-39d4-4d8f-98ff-823fe69b080e