FIX: correctly handling file argument of BROWSE function on Windows

When passing file to BROWSE function, it must be first converted to full local path.

Fixes: metaeducation/rebol-issues#2350

Author: Oldes

src/core/n-io.c

@@ -512,7 +512,12 @@ static REBSER *Read_All_File(char *fname)
 	if (IS_NONE(arg))
 		return R_UNSET;
 
-	url = Val_Str_To_OS(arg);
+	if(IS_FILE(arg)) {
+		// Convert file to full local os path
+		url = UNI_HEAD(Value_To_OS_Path(arg, TRUE));
+	} else {
+		url = Val_Str_To_OS(arg);
+	}
 
 	r = OS_BROWSE(url, 0);