DevTools: Add snapshot command log on the frontend.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 4007 matching lines @@
                     { "name": "toStep", "type": "integer", "optional": true, "description": "The last step to replay to (replay till the end if not specified)." }
                 ],
                 "description": "Replays the layer snapshot and returns the resulting bitmap.",
                 "returns": [
                     { "name": "dataURL", "type": "string", "description": "A data: URL for resulting image." }
                 ]
             },
             {
                 "name": "snapshotCommandLog",
                 "parameters": [
-                    { "name": "snapshotId", "$ref": "SnapshotId", "description": "The id of the layer snapshot." }
+                    { "name": "snapshotId", "$ref": "SnapshotId", "description": "The id of the layer snapshot." },
+                    { "name": "fromStep", "type": "integer", "optional": true, "description": "The first step to get log from (get log from the very start if not specified)." },
+                    { "name": "toStep", "type": "integer", "optional": true, "description": "The last step to get log to (get log till the end if not specified)." }
                 ],
                 "description": "Replays the layer snapshot and returns canvas log.",
                 "returns": [
                     { "name": "commandLog", "type": "array", "items": { "type": "object" }, "description": "The array of canvas function calls." }
                 ]
             }
         ],
         "events": [
             {
                 "name": "layerTreeDidChange",
@@ skipping 136 matching lines @@
             {
                 "name": "dataAvailable",
                 "parameters": [
                     {"name": "value", "type": "array", "items": { "$ref": "PowerEvent" }, "description": "List of power events." }
                 ],
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }