This method is used for %WEBKIT_SCRIPT_DIALOG_PROMPT dialogs when
#WebKitWebView::script-dialog signal is emitted to set the text
entered by the user. The default implementation of #WebKitWebView::script-dialog
signal sets the text of the entry form when OK button is clicked, otherwise %NULL is set.
It's an error to use this method with a #WebKitScriptDialog that is not of type
%WEBKIT_SCRIPT_DIALOG_PROMPT.
This method is used for %WEBKIT_SCRIPT_DIALOG_PROMPT dialogs when #WebKitWebView::script-dialog signal is emitted to set the text entered by the user. The default implementation of #WebKitWebView::script-dialog signal sets the text of the entry form when OK button is clicked, otherwise %NULL is set. It's an error to use this method with a #WebKitScriptDialog that is not of type %WEBKIT_SCRIPT_DIALOG_PROMPT.