Minor fixes

Fixing typos

Author: wks

docs/userguide/src/migration/prefix.md

@@ -80,7 +80,7 @@ See also:
 
 ## 0.27.0
 
-### `is_mmtk_object` returns `Option<ObjectReference>
+### `is_mmtk_object` returns `Option<ObjectReference>`
 
 ```admonish tldr
 `memory_manager::is_mmtk_object` now returns `Option<ObjectReference>` instead of `bool`.

src/util/reference_processor.rs

@@ -223,7 +223,7 @@ impl ReferenceProcessor {
 
     // These funcions call `trace_object()`, which will ensure the object and its descendents will
     // be traced.  They are only called in steps that expand the transitive closure.  That include
-    // retaining soft references, and (for MarkSweep) tracing objects for forwarding.
+    // retaining soft references, and (for MarkCompact) tracing objects for forwarding.
     // Note that finalizers also expand the transitive closure.
     // These functions are intended to make the code easier to understand.
 

src/vm/reference_glue.rs

@@ -28,7 +28,7 @@ pub trait ReferenceGlue<VM: VMBinding> {
     /// Get the referent from a weak reference object.
     ///
     /// Arguments:
-    /// * `object`: Reference to the referent.  `None`` if the object currently does not point to a
+    /// * `object`: Reference to the referent.  `None` if the object currently does not point to a
     ///   referent.  This may happen if the reference has been cleared.
     fn get_referent(object: ObjectReference) -> Option<ObjectReference>;