Parametrize TimelinePresentationModel with coalescable record types

Source/devtools/front_end/timeline/TracingTimelineUIUtils.js

Index: Source/devtools/front_end/timeline/TracingTimelineUIUtils.js
diff --git a/Source/devtools/front_end/timeline/TracingTimelineUIUtils.js b/Source/devtools/front_end/timeline/TracingTimelineUIUtils.js
index 5c4cf0742406ddb00c6c393720b1f81eeb7dbc3f..6a520128df98be6bfdcd1a136568f0429bc8dfd7 100644
--- a/Source/devtools/front_end/timeline/TracingTimelineUIUtils.js
+++ b/Source/devtools/front_end/timeline/TracingTimelineUIUtils.js
@@ -80,6 +80,13 @@ WebInspector.TracingTimelineUIUtils._initEventStyles = function()
     return eventStyles;
 }
 
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes = {};
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes[WebInspector.TracingTimelineModel.RecordType.Layout] = 1;
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes[WebInspector.TracingTimelineModel.RecordType.Paint] = 1;
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes[WebInspector.TracingTimelineModel.RecordType.Rasterize] = 1;
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes[WebInspector.TracingTimelineModel.RecordType.DecodeImage] = 1;
+WebInspector.TracingTimelineUIUtils.coalescableRecordTypes[WebInspector.TracingTimelineModel.RecordType.ResizeImage] = 1;
+
 /**
  * @param {!WebInspector.TracingModel.Event} event
  * @return {!{title: string, category: !WebInspector.TimelineCategory}}