refactor(semantic): use is_empty() instead of len() == 0 (#4532)

It's preferred to use `is_empty` where possible. `is_empty` is sometimes slightly more optimized than `len() == 0`.

crates/oxc_semantic/src/node.rs

@@ -87,7 +87,7 @@ impl<'a> AstNodes<'a> {
 
     #[inline]
     pub fn is_empty(&self) -> bool {
-        self.nodes.len() == 0
+        self.nodes.is_empty()
     }
 
     /// Walk up the AST, iterating over each parent node.

crates/oxc_semantic/src/scope.rs

@@ -41,7 +41,7 @@ impl ScopeTree {
 
     #[inline]
     pub fn is_empty(&self) -> bool {
-        self.len() == 0
+        self.parent_ids.is_empty()
     }
 
     pub fn ancestors(&self, scope_id: ScopeId) -> impl Iterator<Item = ScopeId> + '_ {