Bug 1803222 - Return SyntaxError if fails to parse the moduleURL. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D163501

dom/worklet/Worklet.cpp

@@ -108,6 +108,11 @@ class WorkletFetchHandler final : public PromiseNativeHandler,
     nsresult rv = NS_NewURI(getter_AddRefs(resolvedURI), aModuleURL, nullptr,
                             doc->GetBaseURI());
     if (NS_WARN_IF(NS_FAILED(rv))) {
+      // https://html.spec.whatwg.org/multipage/worklets.html#dom-worklet-addmodule
+      // Step 3. If this fails, then return a promise rejected with a
+      // "SyntaxError" DOMException.
+      rv = NS_ERROR_DOM_SYNTAX_ERR;
+
       promise->MaybeReject(rv);
       return promise.forget();
     }
@@ -115,6 +120,8 @@ class WorkletFetchHandler final : public PromiseNativeHandler,
     nsAutoCString spec;
     rv = resolvedURI->GetSpec(spec);
     if (NS_WARN_IF(NS_FAILED(rv))) {
+      rv = NS_ERROR_DOM_SYNTAX_ERR;
+
       promise->MaybeReject(rv);
       return promise.forget();
     }

testing/web-platform/meta/worklets/audio-worklet-import.https.html.ini

@@ -7,9 +7,6 @@
   [Importing cyclic scripts resolves the given promise]
     expected: FAIL
 
-  [Importing an invalid URL should reject the given promise with a SyntaxError.]
-    expected: FAIL
-
   [Importing a script that has a syntax error should reject the given promise.]
     expected: FAIL