DevTools: Get rid of synchronous XHRs in the frontend code

Source/devtools/front_end/Runtime.js

Index: Source/devtools/front_end/Runtime.js
diff --git a/Source/devtools/front_end/Runtime.js b/Source/devtools/front_end/Runtime.js
index 708667b5d3287b835fbb4178d076147c1cc931d2..4003c80a197dfad1c9155805dc35fa332a769c4e 100644
--- a/Source/devtools/front_end/Runtime.js
+++ b/Source/devtools/front_end/Runtime.js
@@ -35,24 +35,6 @@ var _loadedScripts = {};
 
 /**
  * @param {string} url
- * @return {string}
- */
-function loadResource(url)
-{
-    var xhr = new XMLHttpRequest();
-    xhr.open("GET", url, false);
-    try {
-        xhr.send(null);
-    } catch (e) {
-        console.error(url + " -> " + new Error().stack);
-        throw e;
-    }
-    // xhr.status === 0 if loading from bundle.
-    return xhr.status < 400 ? xhr.responseText : "";
-}
-
-/**
- * @param {string} url
  * @return {!Promise.<string>}
  */
 function loadResourcePromise(url)
@@ -232,74 +214,6 @@ Runtime.isReleaseMode = function()
 }
 
 /**
- * @param {string} moduleName
- * @param {string} workerName
- * @return {!SharedWorker}
- */
-Runtime.startSharedWorker = function(moduleName, workerName)
-{
-    if (Runtime.isReleaseMode())
-        return new SharedWorker(moduleName + "_module.js", workerName);
-
-    var content = loadResource(moduleName + "/module.json");
-    if (!content)
-        throw new Error("Worker is not defined: " + moduleName + " " + new Error().stack);
-    var scripts = JSON.parse(content)["scripts"];
-    if (scripts.length !== 1)
-        throw Error("Runtime.startSharedWorker supports modules with only one script!");
-    return new SharedWorker(moduleName + "/" + scripts[0], workerName);
-}
-
-/**
- * @param {string} moduleName
- * @return {!Worker}
- */
-Runtime.startWorker = function(moduleName)
-{
-    if (Runtime.isReleaseMode())
-        return new Worker(moduleName + "_module.js");
-
-    var content = loadResource(moduleName + "/module.json");
-    if (!content)
-        throw new Error("Worker is not defined: " + moduleName + " " + new Error().stack);
-    var message = [];
-    var scripts = JSON.parse(content)["scripts"];
-    for (var i = 0; i < scripts.length; ++i) {
-        var url = self._importScriptPathPrefix + moduleName + "/" + scripts[i];
-        var parts = url.split("://");
-        url = parts.length === 1 ? url : parts[0] + "://" + normalizePath(parts[1]);
-        message.push({
-            source: loadResource(moduleName + "/" + scripts[i]),
-            url: url
-        });
-    }
-
-    /**
-     * @suppress {checkTypes}
-     */
-    var loader = function() {
-        self.onmessage = function(event) {
-            self.onmessage = null;
-            var scripts = event.data;
-            for (var i = 0; i < scripts.length; ++i) {
-                var source = scripts[i]["source"];
-                self.eval(source + "\n//# sourceURL=" + scripts[i]["url"]);
-            }
-        };
-    };
-
-    var blob = new Blob(["(" + loader.toString() + ")()\n//# sourceURL=" + moduleName], { type: "text/javascript" });
-    var workerURL = window.URL.createObjectURL(blob);
-    try {
-        var worker = new Worker(workerURL);
-        worker.postMessage(message);
-        return worker;
-    } finally {
-        window.URL.revokeObjectURL(workerURL);
-    }
-}
-
-/**
  * @param {string} appName
  */
 Runtime.startApplication = function(appName)
@@ -725,6 +639,7 @@ Runtime.Module.prototype = {
             dependencyPromises.push(this._manager._modulesMap[dependencies[i]]._loadPromise());
 
         this._pendingLoadPromise = Promise.all(dependencyPromises)
+            .then(this._loadStylesheets.bind(this))
             .then(this._loadScripts.bind(this))
             .then(markAsLoaded.bind(this));
 
@@ -742,25 +657,54 @@ Runtime.Module.prototype = {
 
     /**
      * @return {!Promise.<undefined>}
+     * @this {Runtime.Module}
+     */
+    _loadStylesheets: function()
+    {
+        var stylesheets = this._descriptor["stylesheets"];
+        if (!stylesheets)
+            return Promise.resolve();
+        var promises = [];
+        for (var i = 0; i < stylesheets.length; ++i) {
+            var url = this._modularizeURL(stylesheets[i]);
+            promises.push(loadResourcePromise(url).then(cacheStylesheet.bind(this, url), cacheStylesheet.bind(this, url, undefined)));
+        }
+        return Promise.all(promises).then(undefined);
+
+        /**
+         * @param {string} path
+         * @param {string=} content
+         */
+        function cacheStylesheet(path, content)
+        {
+            if (!content) {
+                console.error("Failed to load stylesheet: " + path);
+                return;
+            }
+            Runtime.cachedResources[path] = content;
+        }
+    },
+
+    /**
+     * @return {!Promise.<undefined>}
      */
     _loadScripts: function()
     {
         if (!this._descriptor.scripts)
-            return Promise.resolve(undefined);
+            return Promise.resolve();
 
         if (Runtime.isReleaseMode())
             return loadScriptsPromise([this._name + "_module.js"]);
 
-        return loadScriptsPromise(this._descriptor.scripts.map(modularizeURL, this)).catch(Runtime._reportError);
+        return loadScriptsPromise(this._descriptor.scripts.map(this._modularizeURL, this)).catch(Runtime._reportError);
+    },
 
-        /**
-         * @param {string} scriptName
-         * @this {Runtime.Module}
-         */
-        function modularizeURL(scriptName)
-        {
-            return this._name + "/" + scriptName;
-        }
+    /**
+     * @param {string} resourceName
+     */
+    _modularizeURL: function(resourceName)
+    {
+        return normalizePath(this._name + "/" + resourceName);
     },
 
     /**