Simplify setting instance variables

Since T_OBJECT objects come to life as embedded objects, that means that
ROBJECT_NUMIV will always return a _minimum_ of ROBJECT_EMBED_LEN_MAX.
If ivup.index is *greater* than ROBJECT_NUMIV, then we know that the
object *must not* be an embedded object. Thus we can skip the
ROBJECT_EMBED_LEN_MAX check as well as initializing internals of
embedded objects.

variable.c

@@ -1407,7 +1407,7 @@ obj_ivar_set(VALUE obj, ID id, VALUE val)
 {
     VALUE klass = rb_obj_class(obj);
     struct ivar_update ivup;
-    uint32_t i, len;
+    uint32_t len;
     ivup.iv_extended = 0;
     ivup.u.iv_index_tbl = iv_index_tbl_make(obj, klass);
 
@@ -1420,14 +1420,6 @@ obj_ivar_set(VALUE obj, ID id, VALUE val)
     len = ROBJECT_NUMIV(obj);
     if (len <= ivup.index) {
         VALUE *ptr = ROBJECT_IVPTR(obj);
-        if (ivup.index < ROBJECT_EMBED_LEN_MAX) {
-            RBASIC(obj)->flags |= ROBJECT_EMBED;
-            ptr = ROBJECT(obj)->as.ary;
-            for (i = 0; i < ROBJECT_EMBED_LEN_MAX; i++) {
-                ptr[i] = Qundef;
-            }
-        }
-        else {
         VALUE *newptr;
         uint32_t newsize = iv_index_tbl_newsize(&ivup);
 
@@ -1447,7 +1439,6 @@ obj_ivar_set(VALUE obj, ID id, VALUE val)
         ROBJECT(obj)->as.heap.numiv = newsize;
         ROBJECT(obj)->as.heap.iv_index_tbl = ivup.u.iv_index_tbl;
     }
-    }
     RB_OBJ_WRITE(obj, &ROBJECT_IVPTR(obj)[ivup.index], val);
 
     return val;