DevTools: Refactor nits in DebuggerModel event dispatching.

Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js

Index: Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js
diff --git a/Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js b/Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js
index 5106b7ad981f50edd4bb7c43d63256e12eb3f442..d0b06da55566b6e1ae2da914238bf5624e6b2711 100644
--- a/Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js
+++ b/Source/devtools/front_end/sources/AsyncOperationsSidebarPane.js
@@ -180,8 +180,8 @@ WebInspector.AsyncOperationsSidebarPane.prototype = {
      */
     _onAsyncOperationStarted: function(event)
     {
-        var target = /** @type {!WebInspector.Target} */ (event.data.target);
-        var operation = /** @type {!DebuggerAgent.AsyncOperation} */ (event.data.operation);
+        var target = /** @type {!WebInspector.Target} */ (event.target.target());
+        var operation = /** @type {!DebuggerAgent.AsyncOperation} */ (event.data);
 
         var operationsMap = this._asyncOperationsByTarget.get(target);
         if (!operationsMap) {
@@ -199,8 +199,8 @@ WebInspector.AsyncOperationsSidebarPane.prototype = {
      */
     _onAsyncOperationCompleted: function(event)
     {
-        var target = /** @type {!WebInspector.Target} */ (event.data.target);
-        var operationId = /** @type {number} */ (event.data.operationId);
+        var target = /** @type {!WebInspector.Target} */ (event.target.target());
+        var operationId = /** @type {number} */ (event.data);
 
         var operationsMap = this._asyncOperationsByTarget.get(target);
         if (operationsMap)