DevTools: Move usedHeapSize from TimelineEvent into counters.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2840 matching lines @@
     {
         "domain": "Timeline",
         "description": "Timeline provides its clients with instrumentation records that are generated during the page runtime. Timeline instrumentation can be started and stopped using corresponding commands. While timeline is started, it is generating timeline event records.",
         "types": [
             {
                 "id": "Counters",
                 "type": "object",
                 "properties": [
                     { "name": "documents", "type": "integer", "optional": true },
                     { "name": "nodes", "type": "integer", "optional": true },
-                    { "name": "jsEventListeners", "type": "integer", "optional": true }
+                    { "name": "jsEventListeners", "type": "integer", "optional": true },
+                    { "name": "jsHeapSizeUsed", "type": "number", "optional": true, "description": "Currently used size of JS heap." }
                 ],
                 "description": "Current values of counters.",
                 "hidden": true
             },
             {
                 "id": "TimelineEvent",
                 "type": "object",
                 "properties": [
                     { "name": "type", "type": "string", "description": "Event type." },
                     { "name": "data", "type": "object", "description": "Event data." },
                     { "name": "startTime", "type": "number", "description": "Start time." },
                     { "name": "endTime", "type": "number", "optional": true, "description": "End time." },
                     { "name": "children", "type": "array", "optional": true, "items": { "$ref": "TimelineEvent" }, "description": "Nested records." },
                     { "name": "thread", "type": "string", "optional": true, "hidden": true, "description": "If present, identifies the thread that produced the event." },
                     { "name": "counters", "$ref": "Counters", "optional": true, "hidden": true, "description": "Current values of counters." },
                     { "name": "stackTrace", "$ref": "Console.StackTrace", "optional": true, "hidden": true, "description": "Stack trace." },
                     { "name": "frameId", "type": "string", "optional": true, "hidden": true, "description": "Unique identifier of the frame within the page that the event relates to." },
-                    { "name": "usedHeapSize", "type": "integer", "optional": true, "hidden": true, "description": "Current size of JS heap." },
                     { "name": "usedHeapSizeDelta", "type": "integer", "optional": true, "hidden": true, "description": "JS heap size change." }
                 ],
                 "description": "Timeline record contains information about the recorded activity."
             }
         ],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables timeline. After this call, timeline can be started from within the page (for example upon console.timeline)."
             },
@@ skipping 1233 matching lines @@
                 ],
                 "handlers": ["browser", "frontend"]
             },
             {
                 "name": "tracingComplete",
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }