cloning syntax in templates fixes #470
cloning syntax in templates fixes #470

Originally takeLineContext was implicitly cloning the syntax when it
made new line numbers and other parts of the code were relying on the
fact that two instances of a pattern in a template make two unique
syntax objects.

sweet-js/sweet.js,mozilla/sweet.js,getshuvo/sweet.js,dashersw/sweet.js,dashersw/sweet.js,renyaoxiang/sweet.js,getshuvo/sweet.js,mozilla/sweet.js,sweet-js/sweet.js,sweet-js/sweet-core,renyaoxiang/sweet.js