delete deprecated IO-like methods

This commit deletes
{IO,ARGF,StringIO,Zib::GZipReader}#{bytes,chars,lines,codepoints}, which
have been deprecated since c47c095b9740e7c19d6fdca29ab661c1089221d4.

Note that String also has those methods.  They are neither depreacted
nor deleted because they are not aliases of counterpart each_something.

1 files changed, 4 insertions, 2 deletions

diff --git a/spec/ruby/core/argf/lines_spec.rb b/spec/ruby/core/argf/lines_spec.rb
index 6ca6ff1256..620db4312f 100644
--- a/spec/ruby/core/argf/lines_spec.rb
+++ b/spec/ruby/core/argf/lines_spec.rb
@@ -1,6 +1,8 @@
 require_relative '../../spec_helper'
 require_relative 'shared/each_line'
 
-describe "ARGF.lines" do
-  it_behaves_like :argf_each_line, :lines
+ruby_version_is ''...'2.8' do
+  describe "ARGF.lines" do
+    it_behaves_like :argf_each_line, :lines
+  end
 end