Fix issue 17514770 (https://b2.corp.google.com/issues/17514770)

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 1475 matching lines @@
 
 
 class RawString : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(String);
 
  protected:
   RawObject** from() { return reinterpret_cast<RawObject**>(&ptr()->length_); }
   RawSmi* length_;
   RawSmi* hash_;
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->hash_); }
+
+  friend class Library;
 };
 
 
 class RawOneByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(OneByteString);
 
   // Variable length data follows here.
   uint8_t* data() { OPEN_ARRAY_START(uint8_t, uint8_t); }
 
   friend class ApiMessageReader;
@@ skipping 549 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_