patch 9.0.1045: in a class object members cannot be initialized

Problem:    In a class object members cannot be initialized.
Solution:   Support initializing object members. Make "dissassemble" work on
            an object method.
diff --git a/src/vim9.h b/src/vim9.h
index 91ff6ca..c1d11fc 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -33,7 +33,9 @@
     ISN_SOURCE,	    // source autoload script, isn_arg.number is the script ID
     ISN_INSTR,	    // instructions compiled from expression
     ISN_CONSTRUCT,  // construct an object, using contstruct_T
-    ISN_OBJ_MEMBER, // object member, index is isn_arg.number
+    ISN_GET_OBJ_MEMBER, // object member, index is isn_arg.number
+    ISN_STORE_THIS, // store value in "this" object member, index is
+		    // isn_arg.number
 
     // get and set variables
     ISN_LOAD,	    // push local variable isn_arg.number