Node.js different versions cause parsing issues

When an application is profiled using Node.js v*X* and is then processed using Node.js v*Y*, then it will add the following line as a prefix to the output log: `Testing v8 version different from logging version`

So it may look like this:
```
Testing v8 version different from logging version
{
"code": [
{
…
```

It seems to be fine to remove that warning and load it into speedscope again.