Incorrect selection index after setting an HTML text

[alfogrillo]

Steps to reproduce

• Call setContentFromHtml on the composer model with the string <p><strong>rteoff</strong></p>\n
• Observe the related textUpdate generated by the update.
  • It's a replaceAll
  • Code units: 38 values
  • start: 8
  • end: 8
• The parsed text by HTML is rteoff\n (7 characters)
• Observe the start and the end indexes are two positions after the last valid index (which is 6)
• Observe that model.getContentAsPlainText() is equal to rteoff\n\n (two trailing \n)

Expectation

• The start and end index in the replaceAll update is equal to 7 (the first index after the text set in the model)
• The model.getContentAsPlainText() is equal to rteoff\n

[alfogrillo]

Workaround for iOS -> #817

[alfogrillo]

Fixed by #820