make addStyleRule work in IE<=8
make addStyleRule work in IE<=8

rike422/operatta-js,Operational-Transformation/ot.js,abhishekgahlot/ot.js,pingyuanChen/ot.js,abhishekgahlot/ot.js,pingyuanChen/ot.js,pingyuanChen/ot.js,Operational-Transformation/ot.js,Operational-Transformation/ot.js,abhishekgahlot/ot.js