Add support for appearance.

Only strip the vender prefix if we have a replacement rule, this way we don't disrupt the output css for vender properties that aren't yet supported.

cssprefixer/engine.py

@@ -28,7 +28,9 @@ def magic(ruleset, debug, minify):
             if not hasattr(rule, 'name'):#comments don't have name
                 rules.append(rule)
                 continue
-            rule.name = prefixRegex.sub('', rule.name)
+            name = prefixRegex.sub('', rule.name)
+            if name in tr_rules:
+                rule.name = name
             if rule.cssText in ruleSet:
                 continue
             ruleSet.add(rule.cssText)
@@ -40,7 +42,7 @@ def magic(ruleset, debug, minify):
                 ruleset.style.seq.append(rule, 'Comment')
                 continue
             processor = None
-            try:
+            try:#try except so if anything goes wrong we don't lose the original property
                 if rule.name in tr_rules:
                     processor = tr_rules[rule.name](rule)
                     [ruleset.style.seq.append(prop, 'Property') for prop in processor.get_prefixed_props() if prop]

cssprefixer/rules.py

@@ -275,6 +275,6 @@ def get_base_prop(self):
     'transform-origin': FullReplacementRule,
 
     'display': DisplayReplacementRule,
-
     'opacity': OpacityReplacementRule,
+    'appearance': WebkitReplacementRule,
 }

tests.py

@@ -26,10 +26,22 @@ def test_common_and_opera(self):
         self.assertEqual(cssprefixer.process('a{transform: rotate(10deg)}', minify=True),
                          'a{-webkit-transform:rotate(10deg);-moz-transform:rotate(10deg);-o-transform:rotate(10deg);transform:rotate(10deg)}')
 
+    def test_undefined(self):
+        #test prefixed styles that don't have a rule yet, we use a fake property 
+        #for this test becuase we will never have a rule for this
+        self.assertEqual(cssprefixer.process('a{-webkit-faker: black}', minify=True),
+                         'a{-webkit-faker:black}')
+
     def test_webkit(self):
         self.assertEqual(cssprefixer.process('a{background-clip: padding-box}', minify=True),
                          'a{-webkit-background-clip:padding-box;background-clip:padding-box}')
 
+    def test_appearance(self):
+        #test prefixed styles that don't have a rule yet, we use a fake property 
+        #for this test becuase we will never have a rule for this
+        self.assertEqual(cssprefixer.process('a{-webkit-appearance: none;}', minify=True),
+                         'a{-webkit-appearance:none;appearance:none}')
+
     def test_ie_and_opera(self):
         self.assertEqual(cssprefixer.process('a{text-overflow: ellipsis}', minify=True),
                          'a{-o-text-overflow:ellipsis;-ms-text-overflow:ellipsis;text-overflow:ellipsis}')