Add Autofill preview support for <select> input fields

Source/core/html/HTMLSelectElement.cpp

Index: Source/core/html/HTMLSelectElement.cpp
diff --git a/Source/core/html/HTMLSelectElement.cpp b/Source/core/html/HTMLSelectElement.cpp
index 9b92a7a835faa5613a74d02e5c914d7fd87e62a4..1db7a5517b12c28a635a0b6123ff60b10f34c1a9 100755
--- a/Source/core/html/HTMLSelectElement.cpp
+++ b/Source/core/html/HTMLSelectElement.cpp
@@ -268,6 +268,29 @@ void HTMLSelectElement::setValue(const String &value)
     setSelectedIndex(-1);
 }
 
+String HTMLSelectElement::suggestedValue() const
+{
+    return m_suggestedValue;
+}
+
+void HTMLSelectElement::setSuggestedValue(const String& value)
+{
+    m_suggestedValue = value;
+
+    setValue(value);
+}
+
+// Original selected option value before autofill preview
+String HTMLSelectElement::originalValue() const
+{
+    return m_originalValue;
+}
+
+void HTMLSelectElement::setOriginalValue(const String& value)
+{
+    m_originalValue = value;
+}
+
 bool HTMLSelectElement::isPresentationAttribute(const QualifiedName& name) const
 {
     if (name == alignAttr) {