set ChatInputBar.inputText, the text is moved up

I want to use return key to send message, but the text is moved up when setting inputText to anything text
```swift
extension DemoChatViewController: ChatInputBarDelegate {
func inputBarShouldBeginTextEditing(inputBar: ChattoAdditions.ChatInputBar) -> Bool {
return true
}

func inputBarDidBeginEditing(inputBar: ChattoAdditions.ChatInputBar) {

}

func inputBarDidEndEditing(inputBar: ChattoAdditions.ChatInputBar) {

}

func inputBarDidChangeText(inputBar: ChattoAdditions.ChatInputBar) {
if inputBar.inputText.containsString("\n") {
inputBar.inputText = "aaaa"
}
}

func inputBarSendButtonPressed(inputBar: ChattoAdditions.ChatInputBar) {

}

func inputBar(inputBar: ChattoAdditions.ChatInputBar, shouldFocusOnItem item: ChatInputItemProtocol) -> Bool {
return true
}

func inputBar(inputBar: ChattoAdditions.ChatInputBar, didReceiveFocusOnItem item: ChatInputItemProtocol) {

}
}
```
**before**


**after**


Start with the ChatInputBarDelegate inputBarDidChangeText example and reproduce the issue by assigning inputBar.inputText after a return key is entered. Trace how ChatInputBar updates its text layout and verify that assigning inputText no longer moves the text upward while preserving the shown return-key behavior.

Written by the indexing model from the issue text.