[shell mode] Treat <<< as here string operator
[shell mode] Treat <<< as here string operator

Issue #6512

dperetti/CodeMirror,nightwing/CodeMirror,wingify/CodeMirror,pabloferz/CodeMirror,nightwing/CodeMirror,nightwing/CodeMirror,wingify/CodeMirror,dperetti/CodeMirror,wingify/CodeMirror,dperetti/CodeMirror,hackmdio/CodeMirror,pabloferz/CodeMirror,pabloferz/CodeMirror,hackmdio/CodeMirror,hackmdio/CodeMirror