Revert "jquery.textSelection: Remove hardcoded checks for removed WikiEditor iframe mode"

Appears to have broken CodeEditor

This reverts commit c40b6fa9b0a0e17729a75661f80e7882cb0598e1.

Change-Id: I6d04cb91527defe1fdb0d7fb2a324fe1417a89f7
Merge "Revert "jquery.textSelection: Remove hardcoded checks for removed WikiEditor iframe mode""