diff --git a/addon-sdk/source/lib/toolkit/loader.js b/addon-sdk/source/lib/toolkit/loader.js
index f87b106a0e31..4bffa3283bd0 100644
--- a/addon-sdk/source/lib/toolkit/loader.js
+++ b/addon-sdk/source/lib/toolkit/loader.js
@@ -53,8 +53,10 @@ defineLazyGetter(this, "XulApp", () => {
 const bind = Function.call.bind(Function.bind);
 const getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
 const prototypeOf = Object.getPrototypeOf;
-const getOwnIdentifiers = x => [...Object.getOwnPropertyNames(x),
-                                ...Object.getOwnPropertySymbols(x)];
+function* getOwnIdentifiers(x) {
+  yield* Object.getOwnPropertyNames(x);
+  yield* Object.getOwnPropertySymbols(x);
+}
 
 const NODE_MODULES = new Set([
   "assert",
@@ -125,9 +127,8 @@ function freeze(object) {
 // Returns map of given `object`-s own property descriptors.
 const descriptor = iced(function descriptor(object) {
   let value = {};
-  getOwnIdentifiers(object).forEach(function(name) {
+  for (let name of getOwnIdentifiers(object))
     value[name] = getOwnPropertyDescriptor(object, name)
-  });
   return value;
 });
 Loader.descriptor = descriptor;
@@ -160,11 +161,11 @@ function iced(f) {
 // useful during loader bootstrap when other util modules can't be used &
 // thats only case where this export should be used.
 const override = iced(function override(target, source) {
-  let properties = descriptor(target)
-  let extension = descriptor(source || {})
-  getOwnIdentifiers(extension).forEach(function(name) {
-    properties[name] = extension[name];
-  });
+  let properties = descriptor(target);
+
+  for (let name of getOwnIdentifiers(source || {}))
+    properties[name] = getOwnPropertyDescriptor(source, name);
+
   return Object.defineProperties({}, properties);
 });
 Loader.override = override;
@@ -569,7 +570,7 @@ const load = iced(function load(loader, module) {
   // which completely replace the exports object and still want it
   // frozen need to freeze it themselves.
   if (module.exports === originalExports)
-    freeze(module.exports);
+    Object.freeze(module.exports);
 
   return module;
 });
@@ -583,12 +584,6 @@ function normalizeExt(uri) {
          uri + '.js';
 }
 
-// Strips `rootURI` from `string` -- used to remove absolute resourceURI
-// from a relative path
-function stripBase(rootURI, string) {
-  return string.replace(rootURI, './');
-}
-
 // Utility function to join paths. In common case `base` is a
 // `requirer.uri` but in some cases it may be `baseURI`. In order to
 // avoid complexity we require `baseURI` with a trailing `/`.
@@ -597,14 +592,12 @@ const resolve = iced(function resolve(id, base) {
     return id;
 
   let baseDir = dirname(base);
-  if (!baseDir)
-    return normalize(id);
 
   let resolved = join(baseDir, id);
 
   // Joining and normalizing removes the './' from relative files.
   // We need to ensure the resolution still has the root
-  if (isRelative(base))
+  if (base.startsWith('./'))
     resolved = './' + resolved;
 
   return resolved;
@@ -650,7 +643,7 @@ function resolveRelative(rootURI, modulesDir, id) {
   let resolvedPath = (resolveAsFile(fullId) ||
                       resolveAsDirectory(fullId));
   if (resolvedPath) {
-    return stripBase(rootURI, resolvedPath);
+    return './' + resolvedPath.slice(rootURI.length);
   }
 
   return null;
@@ -901,7 +894,7 @@ const Require = iced(function Require(loader, requirer) {
       // remove it if we have any errors.
       module = modules[uri] = Module(requirement, uri);
       try {
-        freeze(load(loader, module));
+        Object.freeze(load(loader, module));
       }
       catch (e) {
         // Clear out modules cache so we can throw on a second invalid require
@@ -928,12 +921,6 @@ const Require = iced(function Require(loader, requirer) {
     // TODO should get native Firefox modules before doing node-style lookups
     // to save on loading time
     if (isNative) {
-      // If a requireMap is available from `generateMap`, use that to
-      // immediately resolve the node-style mapping.
-      // TODO: write more tests for this use case
-      if (requireMap && requireMap[requirer.id])
-        requirement = requireMap[requirer.id][id];
-
       let { overrides } = manifest.jetpack;
       for (let key in overrides) {
         // ignore any overrides using relative keys
@@ -956,8 +943,6 @@ const Require = iced(function Require(loader, requirer) {
       if (!requirement && modules[id])
         uri = requirement = id;
 
-      // If no requireMap was provided, or resolution not found in
-      // the requireMap, and not a npm dependency, attempt a runtime lookup
       if (!requirement && !NODE_MODULES.has(id)) {
         // If `isNative` defined, this is using the new, native-style
         // loader, not cuddlefish, so lets resolve using node's algorithm
@@ -1225,7 +1210,6 @@ function Loader(options) {
   if (isNative) {
     returnObj.isNative = { enumerable: false, value: true };
     returnObj.manifest = { enumerable: false, value: manifest };
-    returnObj.requireMap = { enumerable: false, value: requireMap };
     returnObj.rootURI = { enumerable: false, value: addTrailingSlash(rootURI) };
   }
 
@@ -1238,9 +1222,7 @@ var isSystemURI = uri => /^resource:\/\/(gre|devtools|testing-common)\//.test(ur
 var isJSONURI = uri => uri.endsWith('.json');
 var isJSMURI = uri => uri.endsWith('.jsm');
 var isJSURI = uri => uri.endsWith('.js');
-var isAbsoluteURI = uri => uri.startsWith("resource://") ||
-                           uri.startsWith("chrome://") ||
-                           uri.startsWith("file://");
+var isAbsoluteURI = uri => /^(resource|chrome|file|jar):/.test(uri);
 var isRelative = id => id.startsWith(".");
 
 // Default `main` entry to './index.js' and ensure is relative,
diff --git a/addon-sdk/source/test/test-native-loader.js b/addon-sdk/source/test/test-native-loader.js
index cc718552249b..c8adfc0780ed 100644
--- a/addon-sdk/source/test/test-native-loader.js
+++ b/addon-sdk/source/test/test-native-loader.js
@@ -110,35 +110,6 @@ for (let variant of variants) {
   };
   */
 
-  exports[`test native Loader with mappings (${variant.description})`] = function (assert, done) {
-    all([
-      getJSON('/fixtures/native-addon-test/expectedmap.json'),
-      getJSON('/fixtures/native-addon-test/package.json')
-    ]).then(([expectedMap, manifest]) => {
-
-      // Override dummy module and point it to `test-math` to see if the
-      // require is pulling from the mapping
-      expectedMap['./index.js']['./dir/dummy'] = './dir/a.js';
-
-      let rootURI = variant.getRootURI('native-addon-test');
-      let loader = Loader({
-        paths: makePaths(rootURI),
-        rootURI: rootURI,
-        manifest: manifest,
-        requireMap: expectedMap,
-        isNative: true
-      });
-
-      let program = main(loader);
-      assert.equal(program.dummyModule, 'dir/a',
-        'The lookup uses the information given in the mapping');
-
-      testLoader(program, assert);
-      unload(loader);
-      done();
-    }).then(null, (reason) => console.error(reason));
-  };
-
   exports[`test native Loader overrides (${variant.description})`] = function*(assert) {
     const expectedKeys = Object.keys(require("sdk/io/fs")).join(", ");
     const manifest = yield getJSON('/fixtures/native-overrides-test/package.json');