Bug 1198982: Don't fail the SW load for an importScripts failure. r=bkelly

dom/workers/ScriptLoader.cpp

@@ -1727,7 +1727,10 @@ ScriptExecutorRunnable::WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate)
     if (NS_FAILED(loadInfo.mLoadResult)) {
       scriptloader::ReportLoadError(aCx, loadInfo.mURL, loadInfo.mLoadResult,
                                     false);
-      aWorkerPrivate->MaybeDispatchLoadFailedRunnable();
+      // Top level scripts only!
+      if (mIsWorkerScript) {
+        aWorkerPrivate->MaybeDispatchLoadFailedRunnable();
+      }
       return true;
     }
 

dom/workers/test/serviceworkers/importscript_worker.js

@@ -6,6 +6,12 @@ function callByScript() {
 importScripts(['importscript.sjs']);
 importScripts(['importscript.sjs']);
 
+try {
+  importScripts(['there-is-nothing-here.js']);
+} catch (ex) {
+  // Importing a non-existent script should not abort the SW load, bug 1198982.
+}
+
 onmessage = function(e) {
   self.clients.matchAll().then(function(res) {
     if (!res.length) {