Added tests and example for v8 profile converter

Author: slonka

examples/v8-profiler/.gitignore

@@ -0,0 +1,9 @@
+.DS_Store
+node_modules
+*.0x
+.__browserify_string_empty.js
+win
+todo
+.vscode
+flamegraph.html
+v8-profile.json

examples/v8-profiler/README.md

@@ -0,0 +1,14 @@
+# 0x-visualize-v8-profile-example
+
+You need curl installed. This will probably work on linux and macOS.
+
+Running:
+
+```bash
+npm i
+./test.sh
+```
+
+Then open flamegraph.html, click on `v8` button and you should see something like this:
+
+![flamegraph](flamegraph.png)

examples/v8-profiler/flamegraph.png

@@ -0,0 +1,36 @@
+const v8Profiler = require('v8-profiler-next')
+const Koa = require('koa')
+const Router = require('koa-router')
+const fs = require('fs')
+const { promisify } = require('util')
+
+const writeFile = promisify(fs.writeFile)
+
+let app = new Koa()
+let router = new Router()
+
+router.get('/', (ctx, next) => {
+  // ctx.router available
+  ctx.body = 'ok'
+})
+
+router.get('/start-profiling', (ctx, next) => {
+  v8Profiler.startProfiling('p1')
+  ctx.body = 'started'
+})
+
+router.get('/stop-profiling', async (ctx, next) => {
+  const result = v8Profiler.stopProfiling('p1')
+  if (result) {
+    await writeFile('./v8-profile.json', JSON.stringify(result))
+    ctx.body = 'saved profile'
+  } else {
+    ctx.body = 'nothing to show'
+  }
+})
+
+app
+  .use(router.routes())
+  .use(router.allowedMethods())
+
+app.listen(3000)