Ruby » Ruby master

• proc.c: fix issues caused by binding created from Method#to_proc.
  [Bug #11163]
• vm.c (vm_cref_new_toplevel): export as rb_vm_cref_new_toplevel().
• test/ruby/test_method.rb: add some assersions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50592 b2dd03c8-39d4-4d8f-98ff-823fe69b080e