## Summary
This patch makes SMS message field scrollable and limits its height to ⅓
of window height (or ⅔ for smaller windows) so messages in conversation
are shown even when writing very long messages.
## Test Plan (and screenshots)
<small>These screenshots are in APNG and WEBP formats. Download them if
your browser does not support this format.</small>
### Before:
Message field height was not limited. Message field could be even higher
than window. That makes first lines of this field and messages in
conversation inaccessible.
### After:
Message field height is limited to ⅓ or ⅔ of window height. When text
content reaches this threshold, scroll bars will show up.
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