Do not report some CSS errors for code valid in other browsers.

Source/core/inspector/InspectorCSSAgent.cpp

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 604 matching lines @@
         int c = string[i];
         if ((c < 'a' || c > 'z') && (c < 'A' || c > 'Z'))
             return i >= 2 && c == '-';
     }
     return false;
 }
 
 static bool hasNonWebkitVendorSpecificPrefix(const CSSParserString& string)
 {
     const size_t stringLength = string.length();
+    // 4 corresponds to "-o-x" - the shortest vendor-prefixed property name.
     if (stringLength < 4 || string[0] != '-')
         return false;
 
     static const char webkitPrefix[] = "-webkit-";
     if (stringLength > 8 && string.startsWithIgnoringCase(webkitPrefix))
         return false;
 
     return string.is8Bit() ? hasVendorSpecificPrefix(string.characters8(), stringLength) : hasVendorSpecificPrefix(string.characters16(), stringLength);
 }
 
+static bool isValidPropertyName(const CSSParserString& content)
+{
+    if (content.equalIgnoringCase("animation")
+        || content.equalIgnoringCase("font-size-adjust")
+        || content.equalIgnoringCase("transform")
+        || content.equalIgnoringCase("user-select")
+        || content.equalIgnoringCase("-webkit-flex-pack")
+        || content.equalIgnoringCase("-webkit-text-size-adjust"))
+        return true;
+
+    return false;
+}
+
 // static
 bool InspectorCSSAgent::cssErrorFilter(const CSSParserString& content, int propertyId, int errorType)
 {
     const size_t contentLength = content.length();
 
     switch (errorType) {
     case CSSParser::PropertyDeclarationError:
         // Ignore errors like "*property: value". This trick is used for IE7: http://stackoverflow.com/questions/4563651/what-does-an-asterisk-do-in-a-css-property-name
         if (contentLength && content[0] == '*')
             return false;
 
         // The "filter" property is commonly used instead of "opacity" for IE9.
         if (propertyId == CSSPropertyFilter)
             return false;
+
         break;
 
     case CSSParser::InvalidPropertyValueError:
         // The "filter" property is commonly used instead of "opacity" for IE9.
         if (propertyId == CSSPropertyFilter)
             return false;
 
         // Value might be a vendor-specific function.
         if (hasNonWebkitVendorSpecificPrefix(content))
             return false;
 
         // IE-only "cursor: hand".
         if (propertyId == CSSPropertyCursor && content.equalIgnoringCase("hand"))
             return false;
 
-        // Ignore properties like "property: value \9". This trick used in bootsrtap for IE-only properies.
-        if (contentLength > 2 && content[contentLength - 2] == '\\' && content[contentLength - 1] == '9')
+        // Ignore properties like "property: value \9" (common IE hack) or "property: value \0" (IE 8 hack).
+        if (contentLength > 2 && content[contentLength - 2] == '\\' && (content[contentLength - 1] == '9' || content[contentLength - 1] == '0'))
             return false;
+
+        // Another hack like "property: value\0/".
+        if (contentLength > 3 && content[contentLength - 3] == '\\' && content[contentLength - 2] == '0' && content[contentLength - 1] == '/')
+            return false;
+
+        // Popular value prefixes valid in other browsers.
+        if (content.startsWithIgnoringCase("linear-gradient"))
+            return false;
+        if (content.startsWithIgnoringCase("-webkit-flexbox"))
+            return false;
+
         break;
 
     case CSSParser::InvalidPropertyError:
         if (hasNonWebkitVendorSpecificPrefix(content))
             return false;
 
         // Another hack to make IE-only property.
         if (contentLength && content[0] == '_')
             return false;
 
         // IE-only set of properties.
         if (content.startsWithIgnoringCase("scrollbar-"))
             return false;
 
-        // Unsupported standard property.
-        if (content.equalIgnoringCase("font-size-adjust"))
+        if (isValidPropertyName(content))
             return false;
+
         break;
+
+    case CSSParser::InvalidRuleError:
+        // Block error reporting for @-rules for now to avoid noise.
+        if (contentLength > 4 && content[0] == '@')
+            return false;
+        return true;
     }
     return true;
 }
 
 InspectorCSSAgent::InspectorCSSAgent(InstrumentingAgents* instrumentingAgents, InspectorCompositeState* state, InspectorDOMAgent* domAgent, InspectorPageAgent* pageAgent)
     : InspectorBaseAgent<InspectorCSSAgent>("CSS", instrumentingAgents, state)
     , m_frontend(0)
     , m_domAgent(domAgent)
     , m_pageAgent(pageAgent)
     , m_lastStyleSheetId(1)
@@ skipping 993 matching lines @@
             documentsToChange.add(element->ownerDocument());
     }
 
     m_nodeIdToForcedPseudoState.clear();
     for (HashSet<Document*>::iterator it = documentsToChange.begin(), end = documentsToChange.end(); it != end; ++it)
         (*it)->styleResolverChanged(RecalcStyleImmediately);
 }
 
 } // namespace WebCore