Bug 1064470 - Increase the experiments forensic log buffer size again. r=bsmedberg

browser/experiments/Experiments.jsm

@@ -368,7 +368,7 @@ Experiments.Experiments = function (policy=new Experiments.Policy()) {
   // crashes. For forensics purposes, keep the last few log
   // messages in memory and upload them in case of crash.
   this._forensicsLogs = [];
-  this._forensicsLogs.length = 10;
+  this._forensicsLogs.length = 20;
   this._log = Object.create(log);
   this._log.log = (level, string, params) => {
     this._forensicsLogs.shift();