Dropbox raised its IPO price range on Wednesday to between $18 and $20 per share, up from $16 to $18 previously. At the midpoint of the range, the file storage company would be worth $8.4 billion after IPO when including options and restricted stock units. However, the new midpoint is still 34% below the share price paid by private investors in the firm’s last fundraising round in 2014, which was...