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

Source/core/css/CSSParserValues.h

Index: Source/core/css/CSSParserValues.h
diff --git a/Source/core/css/CSSParserValues.h b/Source/core/css/CSSParserValues.h
index 79888d6cab00c134f090c66829fac7dc4483d960..a03ca5c16fc5ab826715537e3c1fa33dd319defe 100644
--- a/Source/core/css/CSSParserValues.h
+++ b/Source/core/css/CSSParserValues.h
@@ -101,14 +101,20 @@ struct CSSParserString {
     template <size_t strLength>
     bool startsWithIgnoringCase(const char (&str)[strLength]) const
     {
-        return startsWithIgnoringCase(str, strLength - 1);
+        return containsIgnoringCaseAt(str, strLength - 1, 0);
     }
 
-    bool startsWithIgnoringCase(const char* str, size_t strLength) const
+    template <size_t strLength>
+    bool containsIgnoringCaseAt(const char (&str)[strLength], unsigned offset) const
+    {
+        return containsIgnoringCaseAt(str, strLength - 1, offset);
+    }
+
+    bool containsIgnoringCaseAt(const char* str, size_t strLength, unsigned offset) const
     {
-        if (length() < strLength)
+        if (length() < strLength + offset)
             return false;
-        return is8Bit() ? WTF::equalIgnoringCase(str, characters8(), strLength) : WTF::equalIgnoringCase(str, characters16(), strLength);
+        return is8Bit() ? WTF::equalIgnoringCase(str, characters8() + offset, strLength) : WTF::equalIgnoringCase(str, characters16() + offset, strLength);
     }
 
     operator String() const { return is8Bit() ? String(m_data.characters8, m_length) : String(m_data.characters16, m_length); }