DevTools: switch Timeline frontend into buffered mode and remove the corresponding experiment.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2870 matching lines @@
                 "description": "Enables timeline. After this call, timeline can be started from within the page (for example upon console.timeline)."
             },
             {
                 "name": "disable",
                 "description": "Disables timeline."
             },
             {
                 "name": "start",
                 "parameters": [
                     { "name": "maxCallStackDepth", "optional": true, "type": "integer", "description": "Samples JavaScript stack traces up to <code>maxCallStackDepth</code>, defaults to 5." },
-                    { "name": "bufferEvents", "optional": true, "type": "boolean", "hidden": true, "description": "Whether instrumentation events should be buffered and returned upon <code>stop</code> call." },
                     { "name": "liveEvents", "optional": true, "type": "string", "hidden": true, "description": "Coma separated event types to issue although bufferEvents is set."},
                     { "name": "includeCounters", "optional": true, "type": "boolean", "hidden": true, "description": "Whether counters data should be included into timeline events." },
                     { "name": "includeGPUEvents", "optional": true, "type": "boolean", "hidden": true, "description": "Whether events from GPU process should be collected." }
                 ],
                 "description": "Starts capturing instrumentation events."
             },
             {
                 "name": "stop",
                 "description": "Stops capturing instrumentation events.",
                 "returns": [
@@ skipping 20 matching lines @@
                 "name": "started",
                 "parameters": [
                     { "name": "consoleTimeline", "type": "boolean", "optional": true, "description": "If specified, identifies that timeline was started using console.timeline() call." }
                 ],
                 "description": "Fired when timeline is started.",
                 "hidden": true
             },
             {
                 "name": "stopped",
                 "parameters": [
-                    { "name": "consoleTimeline", "type": "boolean", "optional": true, "description": "If specified, identifies that timeline was started using console.timeline() call." }
+                    { "name": "consoleTimeline", "type": "boolean", "optional": true, "description": "If specified, identifies that timeline was started using console.timeline() call." },
+                    { "name": "events", "type": "array", "items": { "$ref": "TimelineEvent" }, "optional": true, "hidden": true, "description": "Timeline event record data." }
                 ],
                 "description": "Fired when timeline is stopped.",
                 "hidden": true
             }
         ]
     },
     {
         "domain": "Debugger",
         "description": "Debugger domain exposes JavaScript debugging capabilities. It allows setting and removing breakpoints, stepping through execution, exploring stack traces, etc.",
         "types": [
@@ skipping 1312 matching lines @@
             {
                 "name": "dataAvailable",
                 "parameters": [
                     {"name": "value", "type": "array", "items": { "$ref": "PowerEvent" }, "description": "List of power events." }
                 ],
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }