--- a/layout/style/CSSPropFlags.h
+++ b/layout/style/CSSPropFlags.h
@@ -44,15 +44,18 @@ enum class CSSPropFlags : uint8_t
 
   // This property can be animated on the compositor.
   CanAnimateOnCompositor = 1 << 4,
 
   // This property is an internal property that is not represented in
   // the DOM. Properties with this flag are defined in an #ifndef
   // CSS_PROP_LIST_EXCLUDE_INTERNAL section.
   Internal = 1 << 5,
+
+  // Whether this property should be serialized by Servo in getComputedStyle.
+  SerializedByServo = 1 << 6,
 };
 
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(CSSPropFlags)
 
 } // namespace mozilla
 
 #endif // mozilla_CSSPropFlags_h

--- a/layout/style/ServoCSSPropList.mako.py
+++ b/layout/style/ServoCSSPropList.mako.py
@@ -63,30 +63,60 @@ def is_internal(prop):
 
 def method(prop):
     if prop.name == "float":
         return "CssFloat"
     if prop.name.startswith("-x-"):
         return prop.camel_case[1:]
     return prop.camel_case
 
+# Colors, integers and lengths are easy as well.
+#
+# TODO(emilio): This will go away once the rest of the longhands have been
+# moved or perhaps using a blacklist for the ones with non-layout-dependence
+# but other non-trivial dependence like scrollbar colors.
+SERIALIZED_PREDEFINED_TYPES = [
+    "Color",
+    "Integer",
+    "Length",
+    "Opacity",
+]
+
+def serialized_by_servo(prop):
+    # If the property requires layout information, no such luck.
+    if "GETCS_NEEDS_LAYOUT_FLUSH" in prop.flags:
+        return False
+    # No shorthands yet.
+    if prop.type() == "shorthand":
+        return False
+    # Keywords are all fine.
+    if prop.keyword:
+        return True
+    if prop.predefined_type in SERIALIZED_PREDEFINED_TYPES:
+        return True
+    # TODO(emilio): Enable the rest of the longhands.
+    return False
+
+
 def flags(prop):
     result = []
     if prop.explicitly_enabled_in_chrome():
         result.append("EnabledInUASheetsAndChrome")
     elif prop.explicitly_enabled_in_ua_sheets():
         result.append("EnabledInUASheets")
     if is_internal(prop):
         result.append("Internal")
     if prop.enabled_in == "":
         result.append("Inaccessible")
     if "GETCS_NEEDS_LAYOUT_FLUSH" in prop.flags:
         result.append("GetCSNeedsLayoutFlush")
     if "CAN_ANIMATE_ON_COMPOSITOR" in prop.flags:
         result.append("CanAnimateOnCompositor")
+    if serialized_by_servo(prop):
+        result.append("SerializedByServo")
     return ", ".join('"CSSPropFlags::{}"'.format(flag) for flag in result)
 
 def pref(prop):
     if prop.gecko_pref:
         return '"' + prop.gecko_pref + '"'
     return '""'
 
 def sub_properties(prop):

--- a/servo/components/style/properties/data.py
+++ b/servo/components/style/properties/data.py
@@ -221,16 +221,20 @@ class Longhand(object):
             # discrete). For now, it is still non-animatable.
             self.animatable = False
             self.transitionable = False
             self.animation_value_type = None
 
         # See compute_damage for the various values this can take
         self.servo_restyle_damage = servo_restyle_damage
 
+    @staticmethod
+    def type():
+        return "longhand"
+
     def experimental(self, product):
         if product == "gecko":
             return bool(self.gecko_pref)
         return bool(self.servo_pref)
 
     # FIXME(emilio): Shorthand and Longhand should really share a base class.
     def explicitly_enabled_in_ua_sheets(self):
         return self.enabled_in in ["ua", "chrome"]
@@ -356,16 +360,20 @@ class Shorthand(object):
             if sub.transitionable:
                 transitionable = True
                 break
         return transitionable
 
     animatable = property(get_animatable)
     transitionable = property(get_transitionable)
 
+    @staticmethod
+    def type():
+        return "shorthand"
+
     def experimental(self, product):
         if product == "gecko":
             return bool(self.gecko_pref)
         return bool(self.servo_pref)
 
     # FIXME(emilio): Shorthand and Longhand should really share a base class.
     def explicitly_enabled_in_ua_sheets(self):
         return self.enabled_in in ["ua", "chrome"]
@@ -387,16 +395,20 @@ class Alias(object):
         self.camel_case = to_camel_case(self.ident)
         self.original = original
         self.enabled_in = original.enabled_in
         self.servo_pref = original.servo_pref
         self.gecko_pref = gecko_pref
         self.allowed_in_page_rule = original.allowed_in_page_rule
         self.allowed_in_keyframe_block = original.allowed_in_keyframe_block
 
+    @staticmethod
+    def type():
+        return "alias"
+
     def experimental(self, product):
         if product == "gecko":
             return bool(self.gecko_pref)
         return bool(self.servo_pref)
 
     def explicitly_enabled_in_ua_sheets(self):
         return self.enabled_in in ["ua", "chrome"]