Overhaul of RTL plugin loading sequence

src/source/rtl_text_plugin_main_thread.ts

@@ -10,9 +10,23 @@ class RTLMainThreadPlugin extends Evented {
     dispatcher: Dispatcher = getGlobalDispatcher();
     queue: PluginState[] = [];
 
-    async _sendPluginStateToWorker() {
+    private async _sendPluginStateToWorker() {
         await this.dispatcher.broadcast('syncRTLPluginState', {pluginStatus: this.pluginStatus, pluginURL: this.pluginURL});
-        this.fire(new Event('pluginStateChange', {pluginStatus: this.pluginStatus, pluginURL: this.pluginURL}));
+        this.dispatcher.broadcast('syncRTLPluginState', {pluginStatus: this.pluginStatus, pluginURL: this.pluginURL}).then(
+            (broadCastResults: boolean[]) => {
+                // should fire pluginStateChange event only if at least one of the receiver actually changed plugin status
+                if (broadCastResults) {
+                    for (const result of broadCastResults) {
+                        if (result) {
+                            this.fire(new Event('pluginStateChange',
+                                {
+                                    pluginStatus: this.pluginStatus,
+                                    pluginURL: this.pluginURL
+                                }));
+                        }
+                    }
+                }
+            });
     }
 
     getRTLTextPluginStatus() {

src/source/worker.ts

@@ -177,7 +177,12 @@ export default class Worker {
     private async _syncRTLPluginState(map: string, state: PluginState): Promise<boolean> {
         rtlWorkerPlugin.setState(state);
         const pluginURL = rtlWorkerPlugin.getPluginURL();
-        if (state.pluginStatus === 'loaded' && !rtlWorkerPlugin.isParsed() && pluginURL != null) {
+
+        const isLoaded =
+            state.pluginStatus === 'loaded' || // Main Thread: loaded if the completion callback returned successfully
+            rtlWorkerPlugin.applyArabicShaping != null; // Web-worker: loaded if the plugin functions have been compiled
+
+        if (isLoaded && !rtlWorkerPlugin.isParsed() && pluginURL != null) {
             this.self.importScripts(pluginURL);
             const complete = rtlWorkerPlugin.isParsed();
             if (complete) {