Followup r93366: fix Opera bugs in textSelection. All tests pass in Opera now. Before...

Followup r93366: fix Opera bugs in textSelection. All tests pass in Opera now. Before, there were five failures
* replace \r\n with \n in the obtained output from getSelection. This fixes one failure
* In continuation of r93366, which updated post for added newlines in insertText, do the same for pre and also do this in the non-IE branch. This fixes one failure
* Look for \r as well as \n where line endings are concerned in the non-IE branch, just like in the IE branch. This fixes one failure
* Have the test case generator remap selection positions for Opera to account for the fact that a newline is double-counted. This fixes the remaining two failures