refactor(perf): use webdriver to execute benchmarks

- use performance log of chromedriver / appium to get timeline data
  for calculating metrics for benchmarks
- change all benchmarks to be made of a standalone application
  and a protractor test that collectes timeline data
- fix and simplify benchmarks
- add dart2js to build
- remove benchpress

Closes #330

protractor-perf-js.conf.js

@@ -0,0 +1,4 @@
+var config = exports.config = require('./protractor-perf-shared.js').config;
+config.params.lang = 'js';
+config.baseUrl = 'http://localhost:8001/';
+