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

tools/perf/util.js

@@ -0,0 +1,179 @@
+var webdriver = require('protractor/node_modules/selenium-webdriver');
+
+module.exports = {
+  perfLogs: perfLogs,
+  sumTimelineStats: sumTimelineStats,
+  runSimpleBenchmark: runSimpleBenchmark,
+  verifyNoErrors: verifyNoErrors,
+  printObjectAsMarkdown: printObjectAsMarkdown
+};
+
+function perfLogs() {
+  return plainLogs('performance').then(function(entries) {
+    var entriesByMethod = {};
+    entries.forEach(function(entry) {
+      var message = JSON.parse(entry.message).message;
+      var entries = entriesByMethod[message.method];
+      if (!entries) {
+        entries = entriesByMethod[message.method] = [];
+      }
+      entries.push(message.params);
+    });
+    return entriesByMethod;
+  });
+}
+
+// Needed as selenium-webdriver does not forward
+// performance logs in the correct way
+function plainLogs(type) {
+  var webdriver = require('protractor/node_modules/selenium-webdriver');
+  return browser.driver.schedule(
+      new webdriver.Command(webdriver.CommandName.GET_LOG).
+          setParameter('type', type),
+      'WebDriver.manage().logs().get(' + type + ')');
+};
+
+
+function sumTimelineStats(messages) {
+  var recordStats = {
+    script: 0,
+    gc: {
+      time: 0,
+      amount: 0
+    },
+    render: 0
+  };
+  messages.forEach(function(message) {
+    sumTimelineRecordStats(message.record, recordStats);
+  });
+  return recordStats;
+}
+
+function sumTimelineRecordStats(record, result) {
+  var summedChildrenDuration = 0;
+  if (record.children) {
+    record.children.forEach(function(child) {
+      summedChildrenDuration += sumTimelineRecordStats(child, result);
+    });
+  }
+  // in case a script forced a gc or a reflow
+  // we need to substract the gc time / reflow time
+  // from the script time!
+  var recordDuration = (record.endTime ? record.endTime - record.startTime : 0)
+    - summedChildrenDuration;
+
+  var recordSummed = true;
+  if (record.type === 'FunctionCall') {
+    result.script += recordDuration;
+  } else if (record.type === 'GCEvent') {
+    result.gc.time += recordDuration;
+    result.gc.amount += record.data.usedHeapSizeDelta;
+  } else if (record.type === 'RecalculateStyles' ||
+      record.type === 'Layout' ||
+      record.type === 'UpdateLayerTree' ||
+      record.type === 'Paint' ||
+      record.type === 'Rasterize' ||
+      record.type === 'CompositeLayers') {
+    result.render += recordDuration;
+  } else {
+    recordSummed = false;
+  }
+  if (recordSummed) {
+    return recordDuration;
+  } else {
+    return summedChildrenDuration;
+  }
+}
+
+function runSimpleBenchmark(config) {
+  var url = config.url;
+  var buttonSelectors = config.buttons;
+  // TODO: Don't use a fixed number of warmup / measure iterations,
+  // but make this dependent on the variance of the test results!
+  var warmupCount = browser.params.warmupCount;
+  var measureCount = browser.params.measureCount;
+  var name = config.name;
+
+  browser.get(url);
+  // TODO(tbosch): replace this with a proper protractor/ng2.0 integration
+  // and remove this function as well as all method calls.
+  browser.sleep(browser.params.sleepInterval)
+
+  var btns = buttonSelectors.map(function(selector) {
+    return $(selector);
+  });
+
+  multiClick(btns, warmupCount);
+  gc();
+  // empty perflogs queue
+  perfLogs();
+
+  multiClick(btns, measureCount);
+  gc();
+  return perfLogs().then(function(logs) {
+    var stats = sumTimelineStats(logs['Timeline.eventRecorded']);
+    printObjectAsMarkdown(name, stats);
+    return stats;
+  });
+}
+
+function gc() {
+  // TODO(tbosch): this only works on chrome.
+  // For iOS Safari we need an extension to appium...
+  browser.executeScript('window.gc()');
+}
+
+function multiClick(buttons, count) {
+  var actions = browser.actions();
+  for (var i=0; i<count; i++) {
+    buttons.forEach(function(button) {
+      actions.click(button);
+    });
+  }
+  actions.perform();
+}
+
+function verifyNoErrors() {
+  browser.manage().logs().get('browser').then(function(browserLog) {
+    var filteredLog = browserLog.filter(function(logEntry) {
+      return logEntry.level.value > webdriver.logging.Level.WARNING.value;
+    });
+    expect(filteredLog.length).toEqual(0);
+    if (filteredLog.length) {
+      console.log('browser console errors: ' + require('util').inspect(filteredLog));
+    }
+  });
+}
+
+function printObjectAsMarkdown(name, obj) {
+  var props = [['name']];
+  var vals = [name];
+  flattenObj(obj, [], props, vals);
+  // log header
+  var separators = [];
+  var header = props.map(function(propPath) {
+    separators.push('----');
+    return propPath.join('.');
+  }).join(' | ');
+  console.log('\n'+header);
+  console.log(separators.join(' | '));
+  console.log(vals.join(' | '));
+  console.log('\n');
+
+  function flattenObj(obj, propPathPrefix, targetProps, targetVals) {
+    for (var prop in obj) {
+      var val = obj[prop];
+      var currPropPath = propPathPrefix.concat([prop]);
+      if (val && typeof val === 'object') {
+        flattenObj(val, currPropPath, targetProps, targetVals);
+      } else {
+        targetProps.push(currPropPath);
+        var valStr = val;
+        if (typeof val === 'number') {
+          valStr = val.toFixed(2);
+        }
+        targetVals.push(valStr);
+      }
+    }
+  }
+}