Three fixes from the WIP flicker branch that were lost during master merges:
1. Move viewport clear (\x1b[3J\x1b[H\x1b[2J) inside the dimension-change
guard so it only fires when cols/rows actually change. Previously every
resize event cleared the screen even at identical dimensions, causing
visible flicker with no subsequent Ink redraw to repaint.
2. Sync _lastResizeDims in sendResize() so restoreTerminalSize() doesn't
trigger a redundant viewport clear on the next throttledResize tick.
3. Add didScroll tracking to touch events — tap (no scroll) now refocuses
xterm's hidden textarea, fixing mobile keyboard input routing after
tapping the terminal area.
Teigen
2011bd8d89