lib/integral.js
function(expr, context, subIntegral) {
      var simplified = simplify.simplifyCore(expr, context);
      if(!simplified.equals(expr)) {
        return subIntegral(simplified, context, "simplified expression");
      }
    }
function(expr, context, subIntegral) {
      var simplified = simplify.simplifyCore(expr, context);
      if(!simplified.equals(expr)) {
        return subIntegral(simplified, context, "simplified expression");
      }
    }
Simplify constants in the integral