Add nanobench benchmark (#81)

Author: goto-bus-stop

bench/.gitattributes

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+jquery-3.3.1.js -diff

bench/.npmignore

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+jquery-3.3.1.js

bench/index.js

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+var bench = require('nanobench');
+var path = require('path');
+var fs = require('fs');
+var insert = require('../');
+
+bench('jquery', function (b) {
+    var source = fs.readFileSync(path.join(__dirname, 'jquery-3.3.1.js'));
+    b.start();
+    var stream = insert();
+    stream.on('data', function() {});
+    stream.on('end', function () {
+        b.end();
+    });
+    stream.end(source);
+});