Add autofill preview support for Textarea

Source/core/html/HTMLTextAreaElement.cpp

Index: Source/core/html/HTMLTextAreaElement.cpp
diff --git a/Source/core/html/HTMLTextAreaElement.cpp b/Source/core/html/HTMLTextAreaElement.cpp
index 751d378a598c150e50b68a2da65b0f1be8d6dcca..8aaa019200b107d56d059203eac0bee5fec12901 100644
--- a/Source/core/html/HTMLTextAreaElement.cpp
+++ b/Source/core/html/HTMLTextAreaElement.cpp
@@ -433,6 +433,20 @@ void HTMLTextAreaElement::setMaxLength(int newValue, ExceptionState& exceptionSt
         setIntegralAttribute(maxlengthAttr, newValue);
 }
 
+const String& HTMLTextAreaElement::suggestedValue() const
+{
+    return m_suggestedValue;
+}
+
+void HTMLTextAreaElement::setSuggestedValue(const String& value)
+{
+    m_suggestedValue = value;
+    setInnerTextValue(m_suggestedValue);
+    updatePlaceholderVisibility(false);
+    setNeedsStyleRecalc();
+    setFormControlValueMatchesRenderer(true);
+}
+
 String HTMLTextAreaElement::validationMessage() const
 {
     if (!willValidate())