Fix the method name in a comment [ci skip]

numeric.rb

@@ -330,7 +330,7 @@ class Integer
         Primitive.attr! :inline_block, :c_trace
 
         # When no block is given, return an Enumerator that enumerates from `self` to `to`.
-        # Not using `block_defined?` and `to_enum` to keep them unaffected by redefinitions.
+        # Not using `block_given?` and `to_enum` to keep them unaffected by redefinitions.
         unless defined?(yield)
           return Primitive.cexpr! 'SIZED_ENUMERATOR(self, 1, &to, int_downto_size)'
         end