Rollup merge of #96776 - liuw:hir, r=oli-obk

Fix two minor issues in hir.rs

I found these two places in hir.rs which could use a bit of improvements while going through the code.

No functional change.

compiler/rustc_hir/src/hir.rs

@@ -1441,7 +1441,7 @@ pub enum AsyncGeneratorKind {
     /// An explicit `async` block written by the user.
     Block,
 
-    /// An explicit `async` block written by the user.
+    /// An explicit `async` closure written by the user.
     Closure,
 
     /// The `async` block generated as the body of an async function.
@@ -2078,10 +2078,7 @@ pub enum YieldSource {
 
 impl YieldSource {
     pub fn is_await(&self) -> bool {
-        match self {
-            YieldSource::Await { .. } => true,
-            YieldSource::Yield => false,
-        }
+        matches!(self, YieldSource::Await { .. })
     }
 }