Fix problem with format string tokenization

Fixed by just not handling closing curlybrace escaping.

Author: ruabmbua

crates/ra_syntax/src/ast/tokens.rs

@@ -418,14 +418,9 @@ pub trait HasFormatSpecifier: AstToken {
 
                     let mut cloned = chars.clone().take(2);
                     let first = cloned.next().and_then(|next| next.1.as_ref().ok()).copied();
-                    let second = cloned.next().and_then(|next| next.1.as_ref().ok()).copied();
                     if first != Some('}') {
                         continue;
                     }
-                    if second == Some('}') {
-                        // Escaped format end specifier, `}}`
-                        continue;
-                    }
                     skip_char_and_emit(&mut chars, FormatSpecifier::Close, &mut callback);
                 }
                 _ => {