compiler: fix method finalization of unnamed structs.

Used to trigger an ICE on
  var v struct{I}; type I interface{}

Updates issue 7.

From-SVN: r185931

gcc/go/gofrontend/gogo.cc

@@ -1653,8 +1653,12 @@ Finalize_methods::type(Type* t)
       }
 
     case Type::TYPE_STRUCT:
+      // Traverse the field types first in case there is an embedded
+      // field with methods that the struct should inherit.
+      if (t->struct_type()->traverse_field_types(this) == TRAVERSE_EXIT)
+          return TRAVERSE_EXIT;
       t->struct_type()->finalize_methods(this->gogo_);
-      break;
+      return TRAVERSE_SKIP_COMPONENTS;
 
     default:
       break;