Add autofill preview support for Textarea

Source/web/WebTextAreaElement.cpp

Index: Source/web/WebTextAreaElement.cpp
diff --git a/Source/web/WebTextAreaElement.cpp b/Source/web/WebTextAreaElement.cpp
index 59d16bc044b4f4043fe092b2b9ed0320b491bf5b..c4ecd8b95e8db4b88c02170538f32e9b435ce029 100644
--- a/Source/web/WebTextAreaElement.cpp
+++ b/Source/web/WebTextAreaElement.cpp
@@ -50,6 +50,16 @@ WebString WebTextAreaElement::value() const
     return constUnwrap<HTMLTextAreaElement>()->value();
 }
 
+void WebTextAreaElement::setSuggestedValue(const WebString& value)
+{
+    unwrap<HTMLTextAreaElement>()->setSuggestedValue(value);
+}
+
+WebString WebTextAreaElement::suggestedValue() const
+{
+    return constUnwrap<HTMLTextAreaElement>()->suggestedValue();
+}
+
 WebTextAreaElement::WebTextAreaElement(const PassRefPtr<HTMLTextAreaElement>& element)
     : WebFormControlElement(element)
 {