Replace custom template tag with django builtin variant.

wagtail/wagtailadmin/templates/wagtailadmin/edit_handlers/inline_panel.js

@@ -1,10 +1,11 @@
+{% load l10n %}
 {% load wagtailadmin_tags %}
 (function() {
     var panel = InlinePanel({
         formsetPrefix: "id_{{ self.formset.prefix }}",
         emptyChildFormPrefix: "{{ self.empty_child.form.prefix }}",
         canOrder: {% if can_order %}true{% else %}false{% endif %},
-        maxForms: {{ self.formset.max_num|no_thousand_separator }}
+        maxForms: {{ self.formset.max_num|unlocalize }}
     });
 
     {% for child in self.children %}

wagtail/wagtailadmin/templatetags/wagtailadmin_tags.py

@@ -94,14 +94,6 @@ def ellipsistrim(value, max_length):
     return value
 
 
-@register.filter
-def no_thousand_separator(num):
-    """
-    Prevent USE_THOUSAND_SEPARATOR from automatically inserting a thousand separator on this value
-    """
-    return str(num)
-
-
 @register.filter
 def fieldtype(bound_field):
     try:

wagtail/wagtailadmin/tests/test_edit_handlers.py

@@ -781,6 +781,7 @@ class TestInlinePanel(TestCase, WagtailTestUtils):
         Test that the USE_THOUSAND_SEPARATOR setting does not screw up the rendering of numbers
         (specifically maxForms=1000) in the JS initializer:
         https://github.com/wagtail/wagtail/pull/2699
+        https://github.com/wagtail/wagtail/issues/3227
         """
         SpeakerObjectList = ObjectList([
             InlinePanel('speakers', label="Speakers", panels=[
@@ -796,6 +797,7 @@ class TestInlinePanel(TestCase, WagtailTestUtils):
 
         self.assertIn('maxForms: 1000', panel.render_js_init())
 
+
     def test_invalid_inlinepanel_declaration(self):
         with self.ignore_deprecation_warnings():
             self.assertRaises(TypeError, lambda: InlinePanel(label="Speakers"))