Clean up uses of X::CheckedHandle where X::Cast or X::Handle is sufficient.

runtime/vm/object.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 2567 matching lines @@
   class Comments : public ZoneAllocated {
    public:
     static Comments& New(intptr_t count);
 
     intptr_t Length() const;
 
     void SetPCOffsetAt(intptr_t idx, intptr_t pc_offset);
     void SetCommentAt(intptr_t idx, const String& comment);
 
     intptr_t PCOffsetAt(intptr_t idx) const;
-    const String& CommentAt(intptr_t idx) const;
+    RawString* CommentAt(intptr_t idx) const;
 
    private:
     explicit Comments(const Array& comments);
 
     // Layout of entries describing comments.
     enum {
       kPCOffsetEntry = 0,  // PC offset to a comment as a Smi.
       kCommentEntry,  // Comment text as a String.
       kNumberOfEntries
     };
@@ skipping 3640 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_