[Devtools] isTrusted in CustomEvents shown twice in console

Fixed bug where isTrusted would show up twice in console when custom
events were expanded. Caused because isTrusted is Unforgable which
makes it both OwnProperty always and an AccessorProperty.

BUG=607819
R=lushnikov

Review-Url: https://codereview.chromium.org/1942883002
Cr-Commit-Position: refs/heads/master@{#391049}

front_end/sdk/RemoteObject.js

@@ -978,13 +978,25 @@ WebInspector.RemoteObject.loadFromObjectPerProto = function(object, callback)
         if (--resultCounter)
             return;
         if (savedOwnProperties && savedAccessorProperties) {
-            var combinedList = savedAccessorProperties.slice(0);
+            var propertiesMap = new Map();
+            var propertySymbols = [];
+            for (var i = 0; i < savedAccessorProperties.length; i++) {
+                var property = savedAccessorProperties[i];
+                if (property.symbol)
+                    propertySymbols.push(property);
+                else
+                    propertiesMap.set(property.name, property);
+            }
             for (var i = 0; i < savedOwnProperties.length; i++) {
                 var property = savedOwnProperties[i];
-                if (!property.isAccessorProperty())
-                    combinedList.push(property);
+                if (property.isAccessorProperty())
+                    continue;
+                if (property.symbol)
+                    propertySymbols.push(property);
+                else
+                    propertiesMap.set(property.name, property);
             }
-            return callback(combinedList, savedInternalProperties ? savedInternalProperties : null);
+            return callback(propertiesMap.valuesArray().concat(propertySymbols), savedInternalProperties ? savedInternalProperties : null);
         } else {
             callback(null, null);
         }