Reduce test pend truffleruby (#619)

Author: tompng

test/irb/test_cmd.rb

@@ -473,7 +473,6 @@ def test_show_source_alias
     end
 
     def test_show_source_end_finder
-      pend if RUBY_ENGINE == 'truffleruby'
       eval(code = <<-EOS, binding, __FILE__, __LINE__ + 1)
         def show_source_test_method
           unless true
@@ -490,7 +489,6 @@ def show_source_test_method
     end
 
     def test_show_source_private_instance
-      pend if RUBY_ENGINE == 'truffleruby'
       eval(code = <<-EOS, binding, __FILE__, __LINE__ + 1)
         class PrivateInstanceTest
           private def show_source_test_method
@@ -510,7 +508,6 @@ class PrivateInstanceTest
 
 
     def test_show_source_private
-      pend if RUBY_ENGINE == 'truffleruby'
       eval(code = <<-EOS, binding, __FILE__, __LINE__ + 1)
         class PrivateTest
           private def show_source_test_method

test/irb/test_ruby_lex.rb

@@ -598,7 +598,6 @@ def test_do_corresponding_to_loop
     end
 
     def test_local_variables_dependent_code
-      pend if RUBY_ENGINE == 'truffleruby'
       lines = ["a /1#/ do", "2"]
       assert_indent_level(lines, 1)
       assert_code_block_open(lines, true)
@@ -707,7 +706,6 @@ def dynamic_prompt(&block)
     end
 
     def assert_dynamic_prompt(lines, expected_prompt_list)
-      pend if RUBY_ENGINE == 'truffleruby'
       context = build_context
       ruby_lex = RubyLex.new(context)
       dynamic_prompt_executed = false