[modules] Implement namespace imports.

test/mjsunit/modules-namespace3.js

Index: test/mjsunit/modules-namespace3.js
diff --git a/test/mjsunit/modules-circular-valid.js b/test/mjsunit/modules-namespace3.js
similarity index 53%
copy from test/mjsunit/modules-circular-valid.js
copy to test/mjsunit/modules-namespace3.js
index e381eefdbc8242c0a6acd38fe7ac05e1d45d6130..9d74465b2d88bb9af58cfe38baf3cb379e54061a 100644
--- a/test/mjsunit/modules-circular-valid.js
+++ b/test/mjsunit/modules-namespace3.js
@@ -4,4 +4,7 @@
 //
 // MODULE
 
-export {a as b} from "modules-skip-circular-valid.js";
+import * as foo from "modules-namespace3.js";
+export * from "modules-namespace3.js";
+export var bar;
+assertEquals(["bar"], Object.getOwnPropertyNames(foo));