Add Autofill preview support for <select> input fields

Source/core/testing/Internals.h

Index: Source/core/testing/Internals.h
diff --git a/Source/core/testing/Internals.h b/Source/core/testing/Internals.h
index 9891956f5ee3e904c3b2c77bb768bd0a78c646e6..9f7aa5acf5da626730bcd60d80f44fc9fe48f167 100644
--- a/Source/core/testing/Internals.h
+++ b/Source/core/testing/Internals.h
@@ -160,6 +160,8 @@ public:
     bool elementShouldAutoComplete(Element* inputElement, ExceptionState&);
     String suggestedValue(Element*, ExceptionState&);
     void setSuggestedValue(Element*, const String&, ExceptionState&);
+    String originalValue(Element*, ExceptionState&);
+    void setOriginalValue(Element*, const String&, ExceptionState&);
     void setEditingValue(Element* inputElement, const String&, ExceptionState&);
     void setAutofilled(Element*, bool enabled, ExceptionState&);
     void scrollElementToRect(Element*, long x, long y, long w, long h, ExceptionState&);