Bug 1647845 Part 1 - Ignore any properties which aren't valid for a style rule when generating CSS2Properties and testing properties r=emilio

To know the valid rules for each property, we need to put this information
into the Servo prop list and add an appropriate getter to Longhand/Shorthand.

Differential Revision: https://phabricator.services.mozilla.com/D105825

Author: AlaskanEmily

dom/bindings/GenerateCSS2PropertiesWebIDL.py

@@ -25,6 +25,11 @@ def generate(output, idlFilename, dataFile):
     for p in propList:
         if "Internal" in p.flags:
             continue
+
+        # Skip properties which aren't valid in style rules.
+        if "Style" not in p.rules:
+            continue
+
         # Unfortunately, even some of the getters here are fallible
         # (e.g. on nsComputedDOMStyle).
         extendedAttrs = [

layout/style/GenerateServoCSSPropList.py

@@ -100,11 +100,20 @@ def generate_header(output, data):
             if not flags:
                 flags = "CSSPropFlags(0)"
             params = [prop.name, prop.id, method, flags, pref]
-
+        excludes = []
         if is_internal:
-            output.write("#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL\n")
+            excludes.append("CSS_PROP_LIST_EXCLUDE_INTERNAL")
+        if "Style" not in prop.rules:
+            excludes.append("CSS_PROP_LIST_EXCLUDE_NOT_IN_STYLE")
+
+        if excludes:
+            output.write(
+                "#if {}\n".format(
+                    " || ".join("!defined " + exclude for exclude in excludes)
+                )
+            )
         output.write("{}({})\n".format(MACRO_NAMES[prop.type()], ", ".join(params)))
-        if is_internal:
+        if excludes:
             output.write("#endif\n")
 
     output.write(

layout/style/ServoCSSPropList.mako.py

@@ -8,7 +8,7 @@ def _assign_slots(obj, args):
 
 
 class Longhand(object):
-    __slots__ = ["name", "method", "id", "flags", "pref"]
+    __slots__ = ["name", "method", "id", "rules", "flags", "pref"]
 
     def __init__(self, *args):
         _assign_slots(self, args)
@@ -19,7 +19,7 @@ def type():
 
 
 class Shorthand(object):
-    __slots__ = ["name", "method", "id", "flags", "pref", "subprops"]
+    __slots__ = ["name", "method", "id", "rules", "flags", "pref", "subprops"]
 
     def __init__(self, *args):
         _assign_slots(self, args)
@@ -30,7 +30,7 @@ def type():
 
 
 class Alias(object):
-    __slots__ = ["name", "method", "alias_id", "prop_id", "flags", "pref"]
+    __slots__ = ["name", "method", "alias_id", "prop_id", "rules", "flags", "pref"]
 
     def __init__(self, *args):
         _assign_slots(self, args)
@@ -123,6 +123,9 @@ def exposed_on_getcs(prop):
     if prop.type() == "shorthand":
         return "SHORTHAND_IN_GETCS" in prop.flags
 
+def rules(prop):
+    return ", ".join('"{}"'.format(rule) for rule in prop.rule_types_allowed_names())
+
 def flags(prop):
     result = []
     if prop.explicitly_enabled_in_chrome():
@@ -154,15 +157,15 @@ def sub_properties(prop):
 
 data = [
     % for prop in data.longhands:
-    Longhand("${prop.name}", "${method(prop)}", "${prop.ident}", [${flags(prop)}], ${pref(prop)}),
+    Longhand("${prop.name}", "${method(prop)}", "${prop.ident}", [${rules(prop)}], [${flags(prop)}], ${pref(prop)}),
     % endfor
 
     % for prop in data.shorthands:
-    Shorthand("${prop.name}", "${prop.camel_case}", "${prop.ident}", [${flags(prop)}], ${pref(prop)},
+    Shorthand("${prop.name}", "${prop.camel_case}", "${prop.ident}", [${rules(prop)}], [${flags(prop)}], ${pref(prop)},
               [${sub_properties(prop)}]),
     % endfor
 
     % for prop in data.all_aliases():
-    Alias("${prop.name}", "${prop.camel_case}", "${prop.ident}", "${prop.original.ident}", [], ${pref(prop)}),
+    Alias("${prop.name}", "${prop.camel_case}", "${prop.ident}", "${prop.original.ident}", [${rules(prop)}], [], ${pref(prop)}),
     % endfor
 ]

layout/style/nsDOMCSSDeclaration.h

@@ -107,6 +107,7 @@ class nsDOMCSSDeclaration : public nsICSSDeclaration {
   }
 
 #define CSS_PROP_LIST_EXCLUDE_INTERNAL
+#define CSS_PROP_LIST_EXCLUDE_NOT_IN_STYLE
 #define CSS_PROP_LONGHAND(name_, id_, method_, ...) CSS_PROP(id_, method_)
 #define CSS_PROP_SHORTHAND(name_, id_, method_, ...) CSS_PROP(id_, method_)
 #define CSS_PROP_ALIAS(name_, aliasid_, id_, method_, ...) \
@@ -116,6 +117,7 @@ class nsDOMCSSDeclaration : public nsICSSDeclaration {
 #undef CSS_PROP_SHORTHAND
 #undef CSS_PROP_LONGHAND
 #undef CSS_PROP_LIST_EXCLUDE_INTERNAL
+#undef CSS_PROP_LIST_EXCLUDE_NOT_IN_STYLE
 #undef CSS_PROP
 #undef CSS_PROP_PUBLIC_OR_PRIVATE
 

layout/style/test/ListCSSProperties.cpp

@@ -10,6 +10,9 @@
 #include <stdlib.h>
 #include "mozilla/ArrayUtils.h"
 
+// Do not consider properties not valid in style rules
+#define CSS_PROP_LIST_EXCLUDE_NOT_IN_STYLE
+
 // Need an extra level of macro nesting to force expansion of method_
 // params before they get pasted.
 #define STRINGIFY_METHOD(method_) #method_

servo/components/style/properties/data.py

@@ -261,6 +261,11 @@ def __init__(
         self.extra_prefixes = parse_property_aliases(extra_prefixes)
         self.flags = flags.split() if flags else []
 
+    def rule_types_allowed_names(self):
+        for name in RULE_VALUES:
+            if self.rule_types_allowed & RULE_VALUES[name] != 0:
+                yield name
+
     def experimental(self, engine):
         if engine == "gecko":
             return bool(self.gecko_pref)
@@ -598,6 +603,11 @@ def __init__(self, name, original, gecko_pref):
     def type():
         return "alias"
 
+    def rule_types_allowed_names(self):
+        for name in RULE_VALUES:
+            if self.rule_types_allowed & RULE_VALUES[name] != 0:
+                yield name
+
     def experimental(self, engine):
         if engine == "gecko":
             return bool(self.gecko_pref)

testing/web-platform/tests/css/cssom/page-descriptors.html

@@ -0,0 +1,40 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <link rel="author" title="Mozilla" href="https://mozilla.org">
+  <link rel="help" href="https://drafts.csswg.org/cssom/#the-cssstyledeclaration-interface">
+  <title>Page descriptors shouldn't be exposed to CSS Style declarations</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id="target"></div>
+<script>
+'use strict';
+
+let element = document.getElementById("target");
+let computedStyle = window.getComputedStyle(element);
+let style = element.style;
+
+test(t => {
+    assert_equals(computedStyle.size, undefined,
+        "computed style should not have size property");
+    assert_equals(computedStyle.getPropertyValue("size"), "",
+        "computed style getPropertyValue(\"size\") should be empty");
+
+    assert_equals(style.size, undefined,
+        "style should not have size property");
+    assert_equals(style.getPropertyValue("size"), "",
+        "style getPropertyValue(\"size\") should be empty");
+    for(const val of ["initial", "auto", "100px"]){
+        style.setProperty("size", val);
+        assert_false(CSS.supports("size", val));
+        assert_equals(style.size, undefined,
+            "style should not have size property after assigning size=" + val);
+        assert_equals(style.getPropertyValue("size"), "",
+            "style getPropertyValue(\"size\") should be empty after assigning size=" + val);
+    }
+});
+</script>
+</body>
+</html>