Dump information when we hit a FATAL in become

runtime/vm/raw_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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 575 matching lines @@
   void StoreSmi(RawSmi* const* addr, RawSmi* value) {
     // Can't use Contains, as array length is initialized through this method.
     ASSERT(reinterpret_cast<uword>(addr) >= RawObject::ToAddr(this));
     *const_cast<RawSmi**>(addr) = value;
   }
 
   friend class Api;
   friend class ApiMessageReader;  // GetClassId
   friend class Serializer;  // GetClassId
   friend class Array;
+  friend class Become;  // GetClassId
   friend class Bigint;
   friend class ByteBuffer;
   friend class Closure;
   friend class Code;
   friend class Double;
   friend class ForwardPointersVisitor;  // StorePointer
   friend class FreeListElement;
   friend class Function;
   friend class GCMarker;
   friend class ExternalTypedData;
@@ skipping 1817 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_