Use VM type cast and save handles.

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 74 matching lines @@
         VMHandles::AllocateZoneHandle(isolate));                               \
     initializeHandle(obj, raw_ptr);                                            \
     if (!obj->Is##object()) {                                                  \
       FATAL("Handle check failed.");                                           \
     }                                                                          \
     return *obj;                                                               \
   }                                                                            \
   static object& CheckedZoneHandle(RawObject* raw_ptr) {                       \
     return CheckedZoneHandle(Isolate::Current(), raw_ptr);                     \
   }                                                                            \
+  /* T::Cast cannot be applied to a null Object, because the object vtable */  \
+  /* is not setup for type T, although some methods are supposed to work   */  \
+  /* with null, for example Instance::Equals().                            */  \
   static const object& Cast(const Object& obj) {                               \
     ASSERT(obj.Is##object());                                                  \
     return reinterpret_cast<const object&>(obj);                               \
   }                                                                            \
   static Raw##object* null() {                                                 \
     return reinterpret_cast<Raw##object*>(Object::null());                     \
   }                                                                            \
   virtual const char* ToCString() const;                                       \
   static const ObjectKind kInstanceKind = k##object;                           \
  protected:  /* NOLINT */                                                      \
@@ skipping 4962 matching lines @@
 
 
 intptr_t TokenStream::Length() const {
   return Smi::Value(raw_ptr()->length_);
 }
 
 
 Token::Kind TokenStream::KindAt(intptr_t index) const {
   const Object& obj = Object::Handle(TokenAt(index));
   if (obj.IsSmi()) {
-    return static_cast<Token::Kind>(
-        Smi::Value(reinterpret_cast<RawSmi*>(obj.raw())));
+    return static_cast<Token::Kind>(Smi::Cast(obj).Value());
   } else if (obj.IsLiteralToken()) {
-    LiteralToken& token = LiteralToken::Handle();
-    token ^= obj.raw();
-    return token.kind();
+    return LiteralToken::Cast(obj).kind();
   }
   ASSERT(obj.IsString());  // Must be an identifier.
   return Token::kIDENT;
 }
 
 
 void Context::SetAt(intptr_t index, const Instance& value) const {
   StorePointer(InstanceAddr(index), value.raw());
 }
 
 
 intptr_t Stackmap::SizeInBits() const {
   return (Smi::Value(raw_ptr()->bitmap_size_in_bytes_) * kBitsPerByte);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_