Happens on UWP, WSA, WP 8.1 platforms, when using touchscreen keyboard. Reproducible on tablets and phones with touch screens.

Reproducible on 5.2, 5.3, 5.4 versions.

Repro steps:
1. Create a project with UI input field.
2. Build to UWP OR WSA OR WP 8.1.
3. Deploy project on touchscreen device.
4. With touch select the input field. Touchscreen keyboard appears on the screen. Type in some text and delete it with backspace key on touchscreen keyboard.
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Error appears:

A first chance exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll
ArgumentOutOfRangeException: Index and count must refer to a location within the string.
Parameter name: count
at System.String.Remove(Int32 startIndex, Int32 count)
at UnityEngine.UI.InputField.Backspace()
at UnityEngine.UI.InputField.KeyPressed(Event evt)
at UnityEngine.UI.InputField.OnUpdateSelected(BaseEventData eventData)
at UnityEngine.EventSystems.ExecuteEvents.Execute(IUpdateSelectedHandler handler, BaseEventData eventData)
at UnityEngine.EventSystems.ExecuteEvents.Execute[T](GameObject target, BaseEventData eventData, EventFunction`1 functor)
(Filename: <Unknown> Line: 0)