Optimize export-from in System.register - fixes #1722

test/core/fixtures/transformation/optimisation.modules.system/options.json

@@ -0,0 +1,4 @@
+{
+  "modules": "system",
+  "optional": ["optimisation.modules.system"]
+}

test/core/fixtures/transformation/optimisation.modules.system/setters/actual.js

@@ -0,0 +1,8 @@
+export * from "foo";
+export {foo} from "foo";
+export {foo, bar} from "foo";
+export {foo as bar} from "bar";
+export {foo as default} from "bar";
+export {foo as default, bar} from "bar";
+
+export var foo, bar;

test/core/fixtures/transformation/optimisation.modules.system/setters/expected.js

@@ -0,0 +1,33 @@
+System.register(["foo", "bar"], function (_export) {
+  "use strict";
+
+  var foo, bar;
+  return {
+    setters: [function (_foo) {
+      var _exportObj = {};
+
+      for (var _key in _foo) {
+        _exportObj[_key] = _foo[_key];
+      }
+
+      _exportObj["foo"] = _foo.foo;
+      _exportObj["foo"] = _foo.foo;
+      _exportObj["bar"] = _foo.bar;
+
+      _export(_exportObj);
+    }, function (_bar) {
+      var _exportObj2 = {};
+      _exportObj2["bar"] = _bar.foo;
+      _exportObj2["default"] = _bar.foo;
+      _exportObj2["default"] = _bar.foo;
+      _exportObj2["bar"] = _bar.bar;
+
+      _export(_exportObj2);
+    }],
+    execute: function () {
+      _export("foo", foo);
+
+      _export("bar", bar);
+    }
+  };
+});