fix(typings): fix typings which were previously unchecked

Closes #4625

modules/benchpress/src/metric/multi_metric.ts

@@ -42,7 +42,7 @@ export class MultiMetric extends Metric {
   }
 }
 
-function mergeStringMaps(maps: any[]): Object {
+function mergeStringMaps(maps: { [key: string]: string }[]): Object {
   var result = {};
   maps.forEach(
       map => { StringMapWrapper.forEach(map, (value, prop) => { result[prop] = value; }); });

modules/benchpress/src/metric/perflog_metric.ts

@@ -142,7 +142,7 @@ export class PerflogMetric extends Metric {
     });
   }
 
-  _addEvents(events: any[]) {
+  _addEvents(events: { [key: string]: string }[]) {
     var needSort = false;
     events.forEach(event => {
       if (StringWrapper.equals(event['ph'], 'X')) {

modules/benchpress/src/statistic.ts

@@ -5,14 +5,14 @@ export class Statistic {
     return Statistic.calculateStandardDeviation(sample, mean) / mean * 100;
   }
 
-  static calculateMean(samples: any[]) {
+  static calculateMean(samples: number[]) {
     var total = 0;
     // TODO: use reduce
     samples.forEach(x => total += x);
     return total / samples.length;
   }
 
-  static calculateStandardDeviation(samples: any[], mean) {
+  static calculateStandardDeviation(samples: number[], mean) {
     var deviation = 0;
     // TODO: use reduce
     samples.forEach(x => deviation += Math.pow(x - mean, 2));