Bug 1535071 - Use the debugger global scope for worker error reporting if necessary, r=smaug,baku.

Differential Revision: https://phabricator.services.mozilla.com/D24270

--HG--
extra : moz-landing-system : lando

dom/script/ScriptSettings.cpp

@@ -483,6 +483,11 @@ void AutoJSAPI::ReportException() {
       errorGlobal = xpc::PrivilegedJunkScope();
     } else {
       errorGlobal = GetCurrentThreadWorkerGlobal();
+      if (!errorGlobal) {
+        // We might be reporting an error in debugger code that ran before the
+        // worker's global was created. Use the debugger global instead.
+        errorGlobal = GetCurrentThreadWorkerDebuggerGlobal();
+      }
     }
   }
   MOZ_ASSERT(JS_IsGlobalObject(errorGlobal));

dom/workers/RuntimeService.cpp

@@ -2491,5 +2491,17 @@ JSObject* GetCurrentThreadWorkerGlobal() {
   return scope->GetGlobalJSObject();
 }
 
+JSObject* GetCurrentThreadWorkerDebuggerGlobal() {
+  WorkerPrivate* wp = GetCurrentThreadWorkerPrivate();
+  if (!wp) {
+    return nullptr;
+  }
+  WorkerDebuggerGlobalScope* scope = wp->DebuggerGlobalScope();
+  if (!scope) {
+    return nullptr;
+  }
+  return scope->GetGlobalJSObject();
+}
+
 }  // namespace dom
 }  // namespace mozilla

dom/workers/WorkerCommon.h

@@ -32,6 +32,8 @@ JSContext* GetCurrentWorkerThreadJSContext();
 
 JSObject* GetCurrentThreadWorkerGlobal();
 
+JSObject* GetCurrentThreadWorkerDebuggerGlobal();
+
 void CancelWorkersForWindow(nsPIDOMWindowInner* aWindow);
 
 void FreezeWorkersForWindow(nsPIDOMWindowInner* aWindow);