Remove old contents

Author: tatsuya6502

1.9/ja/book/lifetimes.md

@@ -393,16 +393,6 @@ let x: &'static i32 = &FOO;
 <!-- ## Lifetime Elision -->
 ## ライフタイムの省略
 
-<!-- Rust supports powerful local type inference in function bodies, but it’s -->
-<!-- forbidden in item signatures to allow reasoning about the types based on -->
-<!-- the item signature alone. However, for ergonomic reasons a very restricted -->
-<!-- secondary inference algorithm called “lifetime elision” applies in function -->
-<!-- signatures. It infers only based on the signature components themselves and not -->
-<!-- based on the body of the function, only infers lifetime parameters, and does -->
-<!-- this with only three easily memorizable and unambiguous rules. This makes -->
-<!-- lifetime elision a shorthand for writing an item signature, while not hiding -->
-<!-- away the actual types involved as full local inference would if applied to it. -->
-
 <!-- Rust supports powerful local type inference in the bodies of functions but not in their item signatures. -->
 <!-- It's forbidden to allow reasoning about types based on the item signature alone. -->
 <!-- However, for ergonomic reasons, a very restricted secondary inference algorithm called -->