Fix ITextInputMethodClient.SurroundingText
Fix ITextInputMethodClient.SurroundingText

AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit,AvaloniaUI/AvaloniaEdit