patch 8.1.2071: when 'wincolor' is set text property changes highlighting

Problem:    When 'wincolor' is set text property changes highlighting. (Andy
            Stewart)
Solution:   Fix combining colors. (closes #4968)
diff --git a/src/drawline.c b/src/drawline.c
index 5916458..43604c8 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -1367,6 +1367,7 @@
 
 		text_prop_attr = 0;
 		text_prop_combine = FALSE;
+		text_prop_type = NULL;
 		if (text_props_active > 0)
 		{
 		    // Sort the properties on priority and/or starting last.
@@ -1406,8 +1407,11 @@
 # ifdef FEAT_TEXT_PROP
 	    else if (text_prop_type != NULL)
 	    {
-		char_attr = hl_combine_attr(
-			line_attr != 0 ? line_attr : win_attr, text_prop_attr);
+		char_attr = hl_combine_attr(line_attr != 0
+						? line_attr
+						: syntax_attr != 0
+						    ? syntax_attr
+						    : win_attr, text_prop_attr);
 	    }
 # endif
 	    else if (line_attr != 0 && ((fromcol == -10 && tocol == MAXCOL)
diff --git a/src/testdir/dumps/Test_wincolor_01.dump b/src/testdir/dumps/Test_wincolor_01.dump
index 06f45b8..5a5ccf5 100644
--- a/src/testdir/dumps/Test_wincolor_01.dump
+++ b/src/testdir/dumps/Test_wincolor_01.dump
@@ -1,8 +1,8 @@
 | +0#af5f00255#ffd7ff255@1|2| | +0#0000001&@4| +0&#e0e0e08| +0&#ffd7ff255@64
-| +0#af5f00255&@1|1| |1+0#0000001&@4|1+0#0000000#e0e0e08@4| | +0#0000001#ffd7ff255@59
-| +8#af5f00255&@1|0| |2+0#0000000#e0e0e08@4>2+0#0000001#ffd7ff255@5| +8&&@59
+| +0#af5f00255&@1|1| |1+0#0000001&@4|1+0&#e0e0e08@4| | +0&#ffd7ff255@59
+| +8#af5f00255&@1|0| |2+0#0000001#e0e0e08@4>2+0&#ffd7ff255@5| +8&&@59
 | +0#af5f00255&@1|1| |3+0#0000001&| |h|e|r|e+0&#e0e0e08| +0&#ffd7ff255|3| @62
 | +0#af5f00255&@1|2| | +0#0000001&@4| +0&#e0e0e08| +0&#ffd7ff255@64
+| +0#af5f00255&@1|3| |t+0#40ff4011&|h|e| |c|a+0&#e0e0e08|t+0&#ffd7ff255| |i|s| |o+1&&|u|t| +0&&|o|f| |t|h|e| |b|a|g| +0#0000001&@45
 |~+0#4040ff13&| @73
-|~| @73
 |-+2#0000000#ffffff0@1| |V|I|S|U|A|L| |-@1| +0&&@34|2| @8|3|,|6| @10|A|l@1| 
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index 27d7641..7db33bf 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -595,8 +595,13 @@
 
   let lines =<< trim END
 	set cursorline cursorcolumn rnu
-	call setline(1, ["","1111111111","22222222222","3 here 3",""])
+	call setline(1, ["","1111111111","22222222222","3 here 3","","the cat is out of the bag"])
 	set wincolor=Pmenu
+	hi CatLine guifg=green ctermfg=green
+	hi Reverse gui=reverse cterm=reverse
+	syn match CatLine /^the.*/
+	call prop_type_add("foo", {"highlight": "Reverse", "combine": 1})
+	call prop_add(6, 12, {"type": "foo", "end_col": 15})
 	/here
   END
   call writefile(lines, 'Xtest_wincolor')
diff --git a/src/version.c b/src/version.c
index 7f34d2a..840c257 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2071,
+/**/
     2070,
 /**/
     2069,