patch 8.2.4972: Vim9: compilation fails when using dict member when skipping

Problem:    Vim9: compilation fails when using dict member when skipping.
Solution:   Do not generate ISN_USEDICT when skipping. (closes #10433)

src/testdir/test_vim9_expr.vim

@@ -452,6 +452,12 @@ def Test_expr3()
       g:vals = []
       assert_equal(false, g:Record(1) && g:Record(true) && g:Record(0))
       assert_equal([1, true, 0], g:vals)
+
+      var failed = false
+      if false && g:a == g:b.c
+        failed = true
+      endif
+      assert_false(failed)
   END
   v9.CheckDefAndScriptSuccess(lines)
 enddef

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4972,
 /**/
     4971,
 /**/

src/vim9expr.c

@@ -2102,7 +2102,8 @@ compile_subscript(
 
     // Turn "dict.Func" into a partial for "Func" bound to "dict".
     // This needs to be done at runtime to be able to check the type.
-    if (keeping_dict && generate_instr(cctx, ISN_USEDICT) == NULL)
+    if (keeping_dict && cctx->ctx_skip != SKIP_YES
+				  && generate_instr(cctx, ISN_USEDICT) == NULL)
 	return FAIL;
 
     return OK;