Fix backcompat with array definitions

src/de.rs

@@ -634,7 +634,12 @@ impl<'a> Deserializer<'a> {
         } else {
             loop {
                 match self.next()? {
-                    Some(Token::RightBracket) |
+                    Some(Token::RightBracket) => {
+                        if array {
+                            self.eat(Token::RightBracket)?;
+                        }
+                        break
+                    }
                     Some(Token::Newline) |
                     None => break,
                     _ => {}

tests/backcompat.rs

@@ -5,10 +5,15 @@ use serde::de::Deserialize;
 
 #[test]
 fn main() {
-    assert!("[a] foo = 1".parse::<toml::Value>().is_err());
+    let s = "
+        [a] foo = 1
+        [[b]] foo = 1
+    ";
+    assert!(s.parse::<toml::Value>().is_err());
 
-    let mut d = toml::de::Deserializer::new("[a] foo = 1");
+    let mut d = toml::de::Deserializer::new(s);
     d.set_require_newline_after_table(false);
     let value = toml::Value::deserialize(&mut d).unwrap();
     assert_eq!(value["a"]["foo"].as_integer(), Some(1));
+    assert_eq!(value["b"][0]["foo"].as_integer(), Some(1));
 }