Timeline: fix frame offsets in Timeline details

third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js

Index: third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js
index 5351a44a412fae75442cff7a01990815f03962c8..b9b09a21fd964c64fb670b4818dd1d6a69f88284 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js
+++ b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.js
@@ -244,10 +244,6 @@ TimelineModel.TimelineFrameModel = class {
   addTraceEvents(target, events, sessionId) {
     this._target = target;
     this._sessionId = sessionId;
-    if (!events.length)
-      return;
-    if (events[0].startTime < this._minimumRecordTime)
-      this._minimumRecordTime = events[0].startTime;
     for (var i = 0; i < events.length; ++i)
       this._addTraceEvent(events[i]);
   }
@@ -257,6 +253,8 @@ TimelineModel.TimelineFrameModel = class {
    */
   _addTraceEvent(event) {
     var eventNames = TimelineModel.TimelineModel.RecordType;
+    if (event.startTime && event.startTime < this._minimumRecordTime)
+      this._minimumRecordTime = event.startTime;
 
     if (event.name === eventNames.SetLayerTreeId) {
       var sessionId = event.args['sessionId'] || event.args['data']['sessionId'];