Remove custom PartialEq impls for LocalInternedString.

This is on-trend with the recent changes simplifying
`LocalInternedString` and reducing its use.

Author: nnethercote

src/libsyntax/feature_gate/check.rs

@@ -769,7 +769,7 @@ pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],
             }
 
             if let Some(allowed) = allow_features.as_ref() {
-                if allowed.iter().find(|f| *f == name.as_str()).is_none() {
+                if allowed.iter().find(|&f| f == &name.as_str() as &str).is_none() {
                     span_err!(span_handler, mi.span(), E0725,
                               "the feature `{}` is not in the list of allowed features",
                               name);

src/libsyntax/parse/literal.rs

@@ -204,7 +204,7 @@ impl LitKind {
         let (kind, symbol, suffix) = match *self {
             LitKind::Str(symbol, ast::StrStyle::Cooked) => {
                 // Don't re-intern unless the escaped string is different.
-                let s = &symbol.as_str();
+                let s: &str = &symbol.as_str();
                 let escaped = s.escape_default().to_string();
                 let symbol = if escaped == *s { symbol } else { Symbol::intern(&escaped) };
                 (token::Str, symbol, None)

src/libsyntax_pos/symbol.rs

@@ -1201,30 +1201,6 @@ impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for LocalInternedS
     }
 }
 
-impl std::cmp::PartialEq<LocalInternedString> for str {
-    fn eq(&self, other: &LocalInternedString) -> bool {
-        self == other.string
-    }
-}
-
-impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a str {
-    fn eq(&self, other: &LocalInternedString) -> bool {
-        *self == other.string
-    }
-}
-
-impl std::cmp::PartialEq<LocalInternedString> for String {
-    fn eq(&self, other: &LocalInternedString) -> bool {
-        self == other.string
-    }
-}
-
-impl<'a> std::cmp::PartialEq<LocalInternedString> for &'a String {
-    fn eq(&self, other: &LocalInternedString) -> bool {
-        *self == other.string
-    }
-}
-
 impl !Send for LocalInternedString {}
 impl !Sync for LocalInternedString {}