Fix URL handling with tinycss2

URLs used to be dedicated tokens in the CSS specification, but it’s now a
common function unless its value isn’t quoted.

tinycss2 1.1.0 includes this change, and WeasyPrint has to take care of these
two different tokens.

weasyprint/css/utils.py

@@ -564,12 +564,12 @@ def get_image(token, base_url):
     """Parse an <image> token."""
     from ..images import LinearGradient, RadialGradient
 
+    parsed_url = get_url(token, base_url)
+    if parsed_url:
+        assert parsed_url[0] == 'url'
+        if parsed_url[1][0] == 'external':
+            return 'url', parsed_url[1][1]
     if token.type != 'function':
-        parsed_url = get_url(token, base_url)
-        if parsed_url:
-            assert parsed_url[0] == 'url'
-            if parsed_url[1][0] == 'external':
-                return 'url', parsed_url[1][1]
         return
     arguments = split_on_comma(remove_whitespace(token.arguments))
     name = token.lower_name
@@ -594,16 +594,24 @@ def get_image(token, base_url):
                 shape, size, position, 'repeating' in name)
 
 
+def _get_url_tuple(string, base_url):
+    if string.startswith('#'):
+        return ('url', ('internal', unquote(string[1:])))
+    else:
+        return ('url', ('external', safe_urljoin(base_url, string)))
+
+
 def get_url(token, base_url):
     """Parse an <url> token."""
     if token.type == 'url':
-        if token.value.startswith('#'):
-            return ('url', ('internal', unquote(token.value[1:])))
-        else:
-            return ('url', ('external', safe_urljoin(base_url, token.value)))
+        return _get_url_tuple(token.value, base_url)
     elif token.type == 'function':
         if token.name == 'attr':
             return check_attr_function(token, 'url')
+        elif token.name == 'url' and len(token.arguments) in (1, 2):
+            # Ignore url modifiers
+            # See https://drafts.csswg.org/css-values-3/#urls
+            return _get_url_tuple(token.arguments[0].value, base_url)
 
 
 def get_quote(token):

weasyprint/css/validation/descriptors.py

@@ -300,10 +300,9 @@ def pad(tokens, base_url):
                     values[0] = token.int_value
             elif token.type in ('string', 'ident'):
                 values[1] = ('string', token.value)
-            elif token.type == 'function':
-                url = get_url(token, base_url)
-                if url is not None and url[0] == 'url':
-                    values[1] = ('url', url[1])
+            url = get_url(token, base_url)
+            if url is not None and url[0] == 'url':
+                values[1] = ('url', url[1])
 
         if None not in values:
             return tuple(values)

weasyprint/css/validation/properties.py

@@ -179,13 +179,12 @@ def background_image(token, base_url):
 @single_token
 def list_style_image(token, base_url):
     """``list-style-image`` property validation."""
-    if token.type != 'function':
-        if get_keyword(token) == 'none':
-            return 'none', None
-        parsed_url = get_url(token, base_url)
-        if parsed_url:
-            if parsed_url[0] == 'url' and parsed_url[1][0] == 'external':
-                return 'url', parsed_url[1][1]
+    if get_keyword(token) == 'none':
+        return 'none', None
+    parsed_url = get_url(token, base_url)
+    if parsed_url:
+        if parsed_url[0] == 'url' and parsed_url[1][0] == 'external':
+            return 'url', parsed_url[1][1]
 
 
 @property()