When pasting, try to use original range

This functionality was (accidentally?) removed by I8f8a240a. It
stops us from over-zealously balancing data when we can get away
with just pasting the original selected range (e.g. it always wraps
collections of text and content nodes in another paragraph).

Bug: 53364
Change-Id: I93fa56c4e43083993c310e0050087e9d1de1e08b
Merge "When pasting, try to use original range"