Add it like
var jsTasks = function(filename) {
return lazypipe()
.pipe(function() {
return $.if(enabled.maps, $.sourcemaps.init());
})
.pipe($.concat, filename)
.pipe($.ngAnnotate)
.pipe($.uglify)
.pipe(function() {
return $.if(enabled.rev, $.rev());
})
.pipe(function() {
return $.if(enabled.maps, $.sourcemaps.write('.'));
})();
};
Check out Disable uglify in Gulpfile