refactor(perf): introduce benchpress2

Major changes:
- make API more reusable
- format output nicely
- only force gc if needed

Regarding forcing gc:
Forcing gc can change script execution time.
We now don't force gc at first and ignore results where gc happens during script execution.
When we ignored too many results, we switch to forcing gc.

Closes #339

protractor-perf-shared.js

@@ -3,13 +3,13 @@ var config = exports.config = {
   specs: ['modules/*/test/**/*_perf.js'],
 
   params: {
-    // size of the sample to take
-    sampleSize: 10,
-    // error to be used for early exit
-    exitOnErrorLowerThan: 4,
-    // maxium number times the benchmark gets repeated before we output the stats
-    // of the best sample
-    maxRepeatCount: 30
+    timeBenchmark: {
+      // size of the sample to take
+      sampleSize: 10,
+      targetCoefficientOfVariation: 4,
+      timeout: 20000,
+      metrics: ['script', 'render']
+    }
   },
 
   // Disable waiting for Angular as we don't have an integration layer yet...
@@ -54,4 +54,4 @@ if (process.env.TRAVIS) {
       performance: 'ALL'
     }
   };
-}
+}