handle escaped @ else

this commit makes the assumption that
https://github.com/sass/dart-sass/issues/1011 is unintended behavior
and may need to be reverted should dart-sass decide it is intended

src/atrule/if_rule.rs

@@ -8,8 +8,8 @@ use crate::error::SassResult;
 use crate::scope::Scope;
 use crate::selector::Selector;
 use crate::utils::{
-    devour_whitespace, devour_whitespace_or_comment, eat_ident, read_until_closing_curly_brace,
+    devour_whitespace, devour_whitespace_or_comment, peek_ident_no_interpolation,
-    read_until_open_curly_brace,
+    read_until_closing_curly_brace, read_until_open_curly_brace,
 };
 use crate::value::Value;
 use crate::{Stmt, Token};
@@ -50,21 +50,19 @@ impl If {
         let mut else_ = Vec::new();
 
         loop {
-            if toks.peek().is_some() {
+            match toks.peek() {
-                if toks.peek().unwrap().kind == '@' {
+                Some(Token { kind: '@', .. }) => {
-                    let first_char = toks.peek_forward(1).unwrap().kind;
+                    toks.peek_forward(1);
-                    toks.peek_backward(1).unwrap();
+                    let mut ident = peek_ident_no_interpolation(toks, false)?;
-                    if first_char != 'e' && first_char != 'E' {
+                    ident.node.make_ascii_lowercase();
+                    if ident.as_str() != "else" {
+                        toks.reset_view();
                         break;
                     }
-                } else {
+                    toks.take(4).for_each(drop);
-                    break;
+                }
+                Some(..) | None => break,
             }
-                let span_before = toks.next().unwrap().pos;
-                if eat_ident(toks, &Scope::new(), &Selector::new(), span_before)?
-                    .to_ascii_lowercase()
-                    == "else"
-                {
             devour_whitespace(toks);
             if let Some(tok) = toks.next() {
                 devour_whitespace(toks);
@@ -74,8 +72,7 @@ impl If {
                         let cond = read_until_open_curly_brace(toks);
                         toks.next();
                         devour_whitespace(toks);
-                                branches
+                        branches.push(Branch::new(cond, read_until_closing_curly_brace(toks)));
-                                    .push(Branch::new(cond, read_until_closing_curly_brace(toks)));
                         toks.next();
                         devour_whitespace(toks);
                     }
@@ -91,12 +88,6 @@ impl If {
             } else {
                 break;
             }
-                } else {
-                    break;
-                }
-            } else {
-                break;
-            }
         }
         devour_whitespace(toks);
 

tests/if.rs

@@ -88,3 +88,13 @@ test!(
     "@if/* pre 1 */true/* post 1 */{ a { color: red; } }",
     "a {\n  color: red;\n}\n"
 );
+test!(
+    escaped_if,
+    "@\\69 f true {\n  a {\n    color: red;\n  }\n}\n",
+    "a {\n  color: red;\n}\n"
+);
+test!(
+    escaped_else,
+    "@if false {}\n\n@\\65lse {\n  a {\n    color: red;\n  }\n}\n",
+    "a {\n  color: red;\n}\n"
+);

tests/str-escape.rs

@@ -68,11 +68,6 @@ test!(
     "a {\n  color: #{foo}\\-;\n}\n",
     "a {\n  color: foo-;\n}\n"
 );
-test!(
-    escape_recognized_as_at_rule,
-    "@\\69 f true {\n  a {\n    b: c;\n  }\n}\n",
-    "a {\n  b: c;\n}\n"
-);
 test!(
     escape_in_middle,
     "a {\n  color: b\\6cue;\n}\n",