Support non-ascii template filenames.

Fixes #1502.

tornado/template.py

@@ -271,7 +271,7 @@ class Template(object):
         .. versionchanged:: 4.3
            Added ``whitespace`` parameter; deprecated ``compress_whitespace``.
         """
-        self.name = name
+        self.name = escape.native_str(name)
 
         if compress_whitespace is not _UNSET:
             # Convert deprecated compress_whitespace (bool) to whitespace (str).

tornado/test/template_test.py

@@ -173,6 +173,10 @@ try{% set y = 1/x %}
         template = Template('{{ 1 / 2 }}')
         self.assertEqual(template.generate(), '0')
 
+    def test_non_ascii_name(self):
+        loader = DictLoader({u("t\u00e9st.html"): "hello"})
+        self.assertEqual(loader.load(u("t\u00e9st.html")).generate(), b"hello")
+
 
 class StackTraceTest(unittest.TestCase):
     def test_error_line_number_expression(self):