Show information about Symbols in DevTools console.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 643 matching lines @@
             {
                 "id": "RemoteObjectId",
                 "type": "string",
                 "description": "Unique object identifier."
             },
             {
                 "id": "RemoteObject",
                 "type": "object",
                 "description": "Mirror object referencing original JavaScript object.",
                 "properties": [
-                    { "name": "type", "type": "string", "enum": ["object", "function", "undefined", "string", "number", "boolean"], "description": "Object type." },
+                    { "name": "type", "type": "string", "enum": ["object", "function", "undefined", "string", "number", "boolean", "symbol"], "description": "Object type." },
                     { "name": "subtype", "type": "string", "optional": true, "enum": ["array", "null", "node", "regexp", "date"], "description": "Object subtype hint. Specified for <code>object</code> type values only." },
                     { "name": "className", "type": "string", "optional": true, "description": "Object class (constructor) name. Specified for <code>object</code> type values only." },
                     { "name": "value", "type": "any", "optional": true, "description": "Remote object value in case of primitive values or JSON values (if it was requested), or description string if the value can not be JSON-stringified (like NaN, Infinity, -Infinity, -0)." },
                     { "name": "description", "type": "string", "optional": true, "description": "String representation of the object." },
                     { "name": "objectId", "$ref": "RemoteObjectId", "optional": true, "description": "Unique object identifier (for non-primitive values)." },
                     { "name": "preview", "$ref": "ObjectPreview", "optional": true, "description": "Preview containing abbreviated property values.", "hidden": true }
                 ]
             },
             {
                 "id": "ObjectPreview",
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             {
                 "name": "dataAvailable",
                 "parameters": [
                     {"name": "value", "type": "array", "items": { "$ref": "PowerEvent" }, "description": "List of power events." }
                 ],
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }