Fix compatibility with Firefox Nightly

Author: janodvarko

lib/wsm-actor.js

@@ -15,18 +15,42 @@ const Events = require("sdk/event/core");
 // See also: https://bugzilla.mozilla.org/show_bug.cgi?id=912121
 // We can't use the core/devtools.js module since this code is
 // executed on the backend.
-var devtools;
-try {
-  devtools = Cu.import("resource://devtools/shared/Loader.jsm", {}).devtools;
-} catch (err) {
-  try {
-      devtools = Cu.import("resource://gre/modules/devtools/shared/Loader.jsm", {}).devtools;
-  } catch (err) {
-      devtools = Cu.import("resource://gre/modules/devtools/Loader.jsm", {}).devtools;
+function safeImport(...args) {
+  for (var i = 0; i < args.length; i++) {
+    try {
+      return Cu["import"](args[i], {});
+    }
+    /* eslint-disable */
+    catch (err) {
+    }
+    /* eslint-enable */
+  }
+  return {};
+}
+
+function safeRequire(devtools, ...args) {
+  for (var i=0; i<args.length; i++) {
+    try {
+      return devtools["require"](args[i]);
+    }
+    catch (err) {
+    }
   }
+  return {};
 }
+
+const devtools = safeImport(
+  "resource://devtools/shared/Loader.jsm",
+  "resource://gre/modules/devtools/shared/Loader.jsm",
+  "resource://gre/modules/devtools/Loader.jsm"
+).devtools;
+
+const protocol = safeRequire(devtools,
+  "devtools/shared/protocol",
+  "devtools/server/protocol"
+);
+
 const { expectState } = devtools["require"]("devtools/server/actors/common");
-const protocol = devtools["require"]("devtools/server/protocol");
 
 // Platform
 const { XPCOMUtils } = Cu.import("resource://gre/modules/XPCOMUtils.jsm", {});