Bug 966992 - Add a CSS_PROPERTY_ALWAYS_ENABLED_IN_UA_SHEETS bit for properties that are enabled by a pref but that are always enabled in UA sheets. r=cam

layout/style/nsCSSParser.cpp

@@ -247,6 +247,12 @@ public:
                                            uint32_t aLineNumber,
                                            uint32_t aLineOffset);
 
+  nsCSSProperty LookupEnabledProperty(const nsAString& aProperty) {
+    return nsCSSProps::LookupProperty(aProperty, mUnsafeRulesEnabled ?
+                                                   nsCSSProps::eEnabledInUASheets :
+                                                   nsCSSProps::eEnabled);
+  }
+
 protected:
   class nsAutoParseCompoundProperty;
   friend class nsAutoParseCompoundProperty;
@@ -1305,7 +1311,11 @@ CSSParserImpl::ParseProperty(const nsCSSProperty aPropID,
   *aChanged = false;
 
   // Check for unknown or preffed off properties
-  if (eCSSProperty_UNKNOWN == aPropID || !nsCSSProps::IsEnabled(aPropID)) {
+  if (eCSSProperty_UNKNOWN == aPropID ||
+      !(nsCSSProps::IsEnabled(aPropID) ||
+        (mUnsafeRulesEnabled &&
+         nsCSSProps::PropHasFlags(aPropID,
+                                  CSS_PROPERTY_ALWAYS_ENABLED_IN_UA_SHEETS)))) {
     NS_ConvertASCIItoUTF16 propName(nsCSSProps::GetStringValue(aPropID));
     REPORT_UNEXPECTED_P(PEUnknownProperty, propName);
     REPORT_UNEXPECTED(PEDeclDropped);
@@ -1560,8 +1570,7 @@ CSSParserImpl::EvaluateSupportsDeclaration(const nsAString& aProperty,
                                            nsIURI* aBaseURL,
                                            nsIPrincipal* aDocPrincipal)
 {
-  nsCSSProperty propID = nsCSSProps::LookupProperty(aProperty,
-                                                    nsCSSProps::eEnabled);
+  nsCSSProperty propID = LookupEnabledProperty(aProperty);
   if (propID == eCSSProperty_UNKNOWN) {
     return false;
   }
@@ -3701,8 +3710,7 @@ CSSParserImpl::ParseSupportsConditionInParensInsideParens(bool& aConditionMet)
         return false;
       }
 
-      nsCSSProperty propID = nsCSSProps::LookupProperty(propertyName,
-                                                        nsCSSProps::eEnabled);
+      nsCSSProperty propID = LookupEnabledProperty(propertyName);
       if (propID == eCSSProperty_UNKNOWN) {
         if (ExpectSymbol(')', true)) {
           UngetToken();
@@ -5743,7 +5751,7 @@ CSSParserImpl::ParseDeclaration(css::Declaration* aDeclaration,
     }
   } else {
     // Map property name to its ID.
-    propID = nsCSSProps::LookupProperty(propertyName, nsCSSProps::eEnabled);
+    propID = LookupEnabledProperty(propertyName);
     if (eCSSProperty_UNKNOWN == propID ||
         (aContext == eCSSContext_Page &&
          !nsCSSProps::PropHasFlags(propID,

layout/style/nsCSSProps.cpp

@@ -392,7 +392,7 @@ nsCSSProps::LookupProperty(const nsACString& aProperty,
   if (eCSSAliasCount != 0 && res >= eCSSProperty_COUNT) {
     static_assert(eCSSProperty_UNKNOWN < eCSSProperty_COUNT,
                   "assuming eCSSProperty_UNKNOWN doesn't hit this code");
-    if (IsEnabled(res) || aEnabled == eAny) {
+    if (IsEnabled(res, aEnabled)) {
       res = gAliases[res - eCSSProperty_COUNT];
       NS_ABORT_IF_FALSE(0 <= res && res < eCSSProperty_COUNT,
                         "aliases must not point to other aliases");
@@ -400,7 +400,7 @@ nsCSSProps::LookupProperty(const nsACString& aProperty,
       res = eCSSProperty_UNKNOWN;
     }
   }
-  if (res != eCSSProperty_UNKNOWN && aEnabled == eEnabled && !IsEnabled(res)) {
+  if (res != eCSSProperty_UNKNOWN && !IsEnabled(res, aEnabled)) {
     res = eCSSProperty_UNKNOWN;
   }
   return res;
@@ -424,7 +424,7 @@ nsCSSProps::LookupProperty(const nsAString& aProperty, EnabledState aEnabled)
   if (eCSSAliasCount != 0 && res >= eCSSProperty_COUNT) {
     static_assert(eCSSProperty_UNKNOWN < eCSSProperty_COUNT,
                   "assuming eCSSProperty_UNKNOWN doesn't hit this code");
-    if (IsEnabled(res) || aEnabled == eAny) {
+    if (IsEnabled(res, aEnabled)) {
       res = gAliases[res - eCSSProperty_COUNT];
       NS_ABORT_IF_FALSE(0 <= res && res < eCSSProperty_COUNT,
                         "aliases must not point to other aliases");
@@ -432,7 +432,7 @@ nsCSSProps::LookupProperty(const nsAString& aProperty, EnabledState aEnabled)
       res = eCSSProperty_UNKNOWN;
     }
   }
-  if (res != eCSSProperty_UNKNOWN && aEnabled == eEnabled && !IsEnabled(res)) {
+  if (res != eCSSProperty_UNKNOWN && !IsEnabled(res, aEnabled)) {
     res = eCSSProperty_UNKNOWN;
   }
   return res;

layout/style/nsCSSProps.h

@@ -191,6 +191,10 @@ static_assert((CSS_PROPERTY_PARSE_PROPERTY_MASK &
 // flushed.
 #define CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH     (1<<20)
 
+// This property is always enabled in UA sheets.  This is meant to be used
+// together with a pref that enables the property for non-UA sheets.
+#define CSS_PROPERTY_ALWAYS_ENABLED_IN_UA_SHEETS  (1<<21)
+
 /**
  * Types of animatable values.
  */
@@ -251,6 +255,7 @@ public:
   // Given a property string, return the enum value
   enum EnabledState {
     eEnabled,
+    eEnabledInUASheets,
     eAny
   };
   // Looks up the property with name aProperty and returns its corresponding
@@ -436,6 +441,13 @@ public:
     return gPropertyEnabled[aProperty];
   }
 
+  static bool IsEnabled(nsCSSProperty aProperty, EnabledState aEnabled) {
+    return IsEnabled(aProperty) ||
+      (aEnabled == eEnabledInUASheets &&
+       PropHasFlags(aProperty, CSS_PROPERTY_ALWAYS_ENABLED_IN_UA_SHEETS)) ||
+      aEnabled == eAny;
+  }
+
 public:
 
 #define CSSPROPS_FOR_SHORTHAND_SUBPROPERTIES(iter_, prop_)                    \