mobile/bind: initialize imported bound packages

Make sure that a bound package's imported and also bound packages
are initialized before referencing methods and constructors in the
imported packages.

Change-Id: If158aac83c245a33695d3b1648d0dfc37a7313ac
Reviewed-on: https://go-review.googlesource.com/20652
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

bind/java/SeqTest.java

@@ -475,6 +475,11 @@ public class SeqTest extends InstrumentationTestCase {
   }
 
   public void testImportedPkg() {
+    Testpkg.CallImportedI(new Secondpkg.I.Stub() {
+      @Override public long F(long i) {
+        return i;
+      }
+    });
     assertEquals("imported string should match", Secondpkg.HelloString, Secondpkg.Hello());
     Secondpkg.I i = Testpkg.NewImportedI();
     Secondpkg.S s = Testpkg.NewImportedS();