Add autofill preview support for Textarea

Source/core/html/HTMLTextAreaElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 415 matching lines @@
 }
 
 void HTMLTextAreaElement::setMaxLength(int newValue, ExceptionState& exceptionState)
 {
     if (newValue < 0)
         exceptionState.throwDOMException(IndexSizeError, "The value provided (" + String::number(newValue) + ") is not positive or 0.");
     else
         setIntegralAttribute(maxlengthAttr, newValue);
 }
 
+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())
         return String();
 
     if (customError())
         return customValidationMessage();
 
     if (valueMissing())
         return locale().queryString(blink::WebLocalizedString::ValidationValueMissing);
@@ skipping 80 matching lines @@
     }
     placeholder->setTextContent(placeholderText);
 }
 
 bool HTMLTextAreaElement::isInteractiveContent() const
 {
     return true;
 }
 
 }