Remove parsed expression cache.

test/unit/context_unit_test.rb

@@ -469,16 +469,6 @@ class ContextUnitTest < Minitest::Test
 
     refute mock_any.has_been_called?
     assert mock_empty.has_been_called?
-  end 
-
-  def test_variable_lookup_caches_markup
-    mock_scan = Spy.on_instance_method(String, :scan).and_return(["string"])
-
-    @context['string'] = 'string'
-    @context['string']
-    @context['string']
-
-    assert_equal 1, mock_scan.calls.size
   end
 
   def test_context_initialization_with_a_proc_in_environment