Remove iv table size check

iv tables cannot shrink.  If the inline cache was ever set, then there
must be an entry for the instance variable in the iv table.  Just set
the iv list on the object to be equal to the iv index table size, then
set the iv.

vm_insnhelper.c

@@ -1213,21 +1213,14 @@ vm_setivar(VALUE obj, ID id, VALUE val, const rb_iseq_t *iseq, IVC ic, const str
 	    VALUE *ptr = ROBJECT_IVPTR(obj);
 	    index = !is_attr ? ic->entry->index : vm_cc_attr_index(cc)-1;
 
-	    if (index < ROBJECT_NUMIV(obj)) {
-		RB_OBJ_WRITE(obj, &ptr[index], val);
-		RB_DEBUG_COUNTER_INC(ivar_set_ic_hit);
-		return val; /* inline cache hit */
-	    } else {
-                st_table * iv_idx_tbl = RCLASS_IV_INDEX_TBL(rb_class_real(klass));
-                if (index < iv_idx_tbl->num_entries) {
-                    rb_init_iv_list(obj, ROBJECT_NUMIV(obj), iv_idx_tbl->num_entries, iv_idx_tbl);
-                    ptr = ROBJECT_IVPTR(obj);
-                    RB_OBJ_WRITE(obj, &ptr[index], val);
-                    RB_DEBUG_COUNTER_INC(ivar_set_ic_hit);
-                    return val; /* inline cache hit */
-                }
+	    if (index >= ROBJECT_NUMIV(obj)) {
+                st_table * iv_idx_tbl = ROBJECT_IV_INDEX_TBL(obj);
+                rb_init_iv_list(obj, ROBJECT_NUMIV(obj), (uint32_t)iv_idx_tbl->num_entries, iv_idx_tbl);
+                ptr = ROBJECT_IVPTR(obj);
             }
-            RB_DEBUG_COUNTER_INC(ivar_set_ic_miss_oorange);
+            RB_OBJ_WRITE(obj, &ptr[index], val);
+            RB_DEBUG_COUNTER_INC(ivar_set_ic_hit);
+            return val; /* inline cache hit */
 	}
 	else {
 	    struct st_table *iv_index_tbl = ROBJECT_IV_INDEX_TBL(obj);