Benchmark introspecting a schema built from SDL in a supplied file.

Use it like so:

```shell
yarn run benchmark
````

Additionally there is a profile command which runs the benchmark with `--prof`:

```shell
yarn run profile
````

Note that on Ubuntu 16.04 this requires:

```shell
sudo apt install linux-tools-common gawk linux-tools-generic linux-tools-4.10.0-35-generic
sudo sh -c 'echo 1 >/proc/sys/kernel/perf_event_paranoid'
```

On my laptop it produces this:

```
$ yarn run benchmark

> [email protected] benchmark /home/osboxes/graphql-js
> babel-node ./resources/benchmark/run.js

introspectionQuery x 24.59 ops/sec ±3.87% (45 runs sampled)
```

package.json

@@ -39,6 +39,8 @@
     "watch": "babel-node ./resources/watch.js",
     "cover": "babel-node ./node_modules/.bin/isparta cover --root src --report html _mocha -- $npm_package_options_mocha",
     "cover:lcov": "babel-node ./node_modules/.bin/isparta cover --root src --report lcovonly _mocha -- $npm_package_options_mocha",
+    "benchmark": "babel-node ./resources/benchmark/run.js",
+    "profile": "perf record -e cycles:u -g -- babel-node --perf-basic-prof ./resources/benchmark/run.js && perf script |./node_modules/stackvis/cmd/stackvis perf >flamegraph.html && echo 'Now view flamegraph.html'",
     "preversion": ". ./resources/checkgit.sh && npm test",
     "prepublish": ". ./resources/prepublish.sh",
     "gitpublish": ". ./resources/gitpublish.sh"
@@ -56,6 +58,7 @@
     "babel-plugin-transform-flow-strip-types": "6.22.0",
     "babel-plugin-transform-object-rest-spread": "6.23.0",
     "babel-preset-env": "^1.5.2",
+    "benchmark": "^2.1.4",
     "chai": "4.1.1",
     "chai-json-equal": "0.0.1",
     "chai-spies-next": "^0.8.0",
@@ -69,6 +72,7 @@
     "isparta": "4.0.0",
     "mocha": "3.5.0",
     "prettier": "^1.8.2",
-    "sane": "2.0.0"
+    "sane": "2.0.0",
+    "stackvis": "^0.5.0"
   }
 }