Skip locking span interner for some syntax context checks

compiler/rustc_span/src/lib.rs

@@ -564,12 +564,6 @@ impl Span {
         !self.is_dummy() && sm.is_span_accessible(self)
     }
 
-    /// Returns `true` if this span comes from any kind of macro, desugaring or inlining.
-    #[inline]
-    pub fn from_expansion(self) -> bool {
-        !self.ctxt().is_root()
-    }
-
     /// Returns `true` if `span` originates in a derive-macro's expansion.
     pub fn in_derive_expansion(self) -> bool {
         matches!(self.ctxt().outer_expn_data().kind, ExpnKind::Macro(MacroKind::Derive, _))