Forcibly silenced some warnings

These tests all rely specifically on odd uses of Ruby that generate
warnings, so just silence them.

test/engine_test.rb

@@ -731,7 +731,8 @@ HAML
   end
 
   def test_silent_script_with_hyphen_end_and_block
-    assert_equal(<<HTML, render(<<HAML))
+    silence_warnings do
+      assert_equal(<<HTML, render(<<HAML))
 <p>foo-end</p>
 <p>bar-end</p>
 HTML
@@ -1152,7 +1153,9 @@ HAML
   EXCEPTION_MAP.each do |key, value|
     define_method("test_exception (#{key.inspect})") do
       begin
-        render(key, :filename => "(test_exception (#{key.inspect}))")
+        silence_warnings do
+          render(key, :filename => "(test_exception (#{key.inspect}))")
+        end
       rescue Exception => err
         value = [value] unless value.is_a?(Array)
         expected_message, line_no = value

test/template_test.rb

@@ -91,9 +91,11 @@ class TemplateTest < MiniTest::Unit::TestCase
       render_method ||= proc { |n| @base.render(:file => n) }
     end
 
-    load_result(name).split("\n").zip(render_method[name].split("\n")).each_with_index do |pair, line|
-      message = "template: #{name}\nline:     #{line}"
-      assert_equal(pair.first, pair.last, message)
+    silence_warnings do
+      load_result(name).split("\n").zip(render_method[name].split("\n")).each_with_index do |pair, line|
+        message = "template: #{name}\nline:     #{line}"
+        assert_equal(pair.first, pair.last, message)
+      end
     end
   rescue Haml::Util.av_template_class(:Error) => e
     if e.message =~ /Can't run [\w:]+ filter; required (one of|file) ((?:'\w+'(?: or )?)+)(, but none were found| not found)/