core: use assoc types in Iterator et al

Author: Jorge Aparicio

src/libcore/char.rs

@@ -446,7 +446,9 @@ enum EscapeUnicodeState {
     Done,
 }
 
-impl Iterator<char> for EscapeUnicode {
+impl Iterator for EscapeUnicode {
+    type Item = char;
+
     fn next(&mut self) -> Option<char> {
         match self.state {
             EscapeUnicodeState::Backslash => {
@@ -501,7 +503,9 @@ enum EscapeDefaultState {
     Unicode(EscapeUnicode),
 }
 
-impl Iterator<char> for EscapeDefault {
+impl Iterator for EscapeDefault {
+    type Item = char;
+
     fn next(&mut self) -> Option<char> {
         match self.state {
             EscapeDefaultState::Backslash(c) => {