patch 8.2.1425: Vim9: cannot use call() without :call

Problem:    Vim9: cannot use call() without :call.
Solution:   Do not skip over "call(". (closes #6689)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 72c26ce..53dca80 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -6484,8 +6484,15 @@
 	cmdmod = save_cmdmod;
 
 	// Skip ":call" to get to the function name.
+	p = ea.cmd;
 	if (checkforcmd(&ea.cmd, "call", 3))
-	    ea.cmd = skipwhite(ea.cmd);
+	{
+	    if (*ea.cmd == '(')
+		// not for "call()"
+		ea.cmd = p;
+	    else
+		ea.cmd = skipwhite(ea.cmd);
+	}
 
 	if (!starts_with_colon)
 	{