patch 8.2.4489: failing test for comparing v:null with number

Problem:    Failing test for comparing v:null with number.
Solution:   Allow comparing v:null with number in legacy script.
            (Ken Takata, closes #9873)  Also do this for float.

src/testdir/test_vimscript.vim

@@ -6546,9 +6546,16 @@ func Test_type()
     call assert_true(v:true != v:false)
 
     call assert_true(v:null == 0)
+    call assert_false(v:null == 1)
     call assert_false(v:null != 0)
     call assert_true(v:none == 0)
+    call assert_false(v:none == 1)
     call assert_false(v:none != 0)
+    if has('float')
+      call assert_true(v:null == 0.0)
+      call assert_false(v:null == 0.1)
+      call assert_false(v:null != 0.0)
+    endif
 
     call assert_true(v:false is v:false)
     call assert_true(v:true is v:true)

src/typval.c

@@ -1405,6 +1405,15 @@ typval_compare_null(typval_T *tv1, typval_T *tv2)
 	    case VAR_LIST: return tv->vval.v_list == NULL;
 	    case VAR_PARTIAL: return tv->vval.v_partial == NULL;
 	    case VAR_STRING: return tv->vval.v_string == NULL;
+
+	    case VAR_NUMBER: if (!in_vim9script())
+				 return tv->vval.v_number == 0;
+			     break;
+#ifdef FEAT_FLOAT
+	    case VAR_FLOAT: if (!in_vim9script())
+				 return tv->vval.v_float == 0.0;
+			     break;
+#endif
 	    default: break;
 	}
     }

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4489,
 /**/
     4488,
 /**/