patch 8.2.2124: Vim9: a range cannot be computed at runtime

Problem:    Vim9: a range cannot be computed at runtime.
Solution:   Add the ISN_RANGE instruction.
diff --git a/src/vim9.h b/src/vim9.h
index 1368b38..88cc4fc 100644
--- a/src/vim9.h
+++ b/src/vim9.h
@@ -18,6 +18,7 @@
     ISN_EXECUTE,    // execute Ex commands isn_arg.number items on top of stack
     ISN_ECHOMSG,    // echo Ex commands isn_arg.number items on top of stack
     ISN_ECHOERR,    // echo Ex commands isn_arg.number items on top of stack
+    ISN_RANGE,	    // compute range from isn_arg.string, push to stack
 
     // get and set variables
     ISN_LOAD,	    // push local variable isn_arg.number
@@ -366,3 +367,8 @@
 extern garray_T def_functions;
 #endif
 
+// Used for "lnum" when a range is to be taken from the stack.
+#define LNUM_VARIABLE_RANGE -999
+
+// Used for "lnum" when a range is to be taken from the stack and "!" is used.
+#define LNUM_VARIABLE_RANGE_ABOVE -888