Add support for case-insensitive attribute value selectors

Source/core/css/CSSSelector.cpp

Index: Source/core/css/CSSSelector.cpp
diff --git a/Source/core/css/CSSSelector.cpp b/Source/core/css/CSSSelector.cpp
index 94238d4c17481b5b12a844c5c404e252577c8dc6..9f824e768aebb673599dc81d61b7a8480ca15fcd 100644
--- a/Source/core/css/CSSSelector.cpp
+++ b/Source/core/css/CSSSelector.cpp
@@ -681,6 +681,8 @@ String CSSSelector::selectorText(const String& rightSide) const
             }
             if (cs->m_match != CSSSelector::Set) {
                 serializeString(cs->value(), str);
+                if (cs->attributeFlags() & CaseInsensitive)
+                    str.append(" i");
                 str.append(']');
             }
         }
@@ -710,10 +712,11 @@ String CSSSelector::selectorText(const String& rightSide) const
     return str.toString() + rightSide;
 }
 
-void CSSSelector::setAttribute(const QualifiedName& value)
+void CSSSelector::setAttribute(const QualifiedName& value, unsigned flags)
 {
     createRareData();
     m_data.m_rareData->m_attribute = value;
+    m_data.m_rareData->m_attributeFlags = flags;
 }
 
 void CSSSelector::setArgument(const AtomicString& value)
@@ -817,6 +820,7 @@ CSSSelector::RareData::RareData(const AtomicString& value)
     , m_a(0)
     , m_b(0)
     , m_attribute(anyQName())
+    , m_attributeFlags(NoAttributeFlags)
     , m_argument(nullAtom)
 {
 }