DevTools: Get rid of synchronous XHRs in the frontend code

Source/devtools/front_end/sources/FilteredItemSelectionDialog.js

Index: Source/devtools/front_end/sources/FilteredItemSelectionDialog.js
diff --git a/Source/devtools/front_end/sources/FilteredItemSelectionDialog.js b/Source/devtools/front_end/sources/FilteredItemSelectionDialog.js
index 4743506a9e01bb5ab68ff2d153d9280ff91b13a6..d979e51f0c3d357b7f3dc32293cdbbbf9d2e100c 100644
--- a/Source/devtools/front_end/sources/FilteredItemSelectionDialog.js
+++ b/Source/devtools/front_end/sources/FilteredItemSelectionDialog.js
@@ -531,9 +531,8 @@ WebInspector.JavaScriptOutlineDialog = function(uiSourceCode, selectItemCallback
 
     this._functionItems = [];
     this._selectItemCallback = selectItemCallback;
-    this._outlineWorker = Runtime.startWorker("script_formatter_worker");
-    this._outlineWorker.onmessage = this._didBuildOutlineChunk.bind(this);
-    this._outlineWorker.postMessage({ method: "javaScriptOutline", params: { content: uiSourceCode.workingCopy() } });
+    this._uiSourceCode = uiSourceCode;
+    WorkerRuntime.startWorker("script_formatter_worker").then(this._init.bind(this));
 }
 
 /**
@@ -551,6 +550,16 @@ WebInspector.JavaScriptOutlineDialog.show = function(view, uiSourceCode, selectI
 
 WebInspector.JavaScriptOutlineDialog.prototype = {
     /**
+     * @param {!Worker} worker
+     */
+    _init: function(worker)
+    {
+        this._outlineWorker = worker;
+        this._outlineWorker.onmessage = this._didBuildOutlineChunk.bind(this);
+        this._outlineWorker.postMessage({ method: "javaScriptOutline", params: { content: this._uiSourceCode.workingCopy() } });
+    },
+
+    /**
      * @param {!MessageEvent} event
      */
     _didBuildOutlineChunk: function(event)