Avoid allocating an exception object in the snapshot reader.

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 <limits>
 #include "include/dart_api.h"
 #include "platform/assert.h"
@@ skipping 4153 matching lines @@
     return RoundedAllocationSize(sizeof(RawUnhandledException));
   }
 
   static RawUnhandledException* New(const Instance& exception,
                                     const Instance& stacktrace,
                                     Heap::Space space = Heap::kNew);
 
   virtual const char* ToErrorCString() const;
 
  private:
+  static RawUnhandledException* New(Heap::Space space = Heap::kNew);
+
   void set_exception(const Instance& exception) const;
   void set_stacktrace(const Instance& stacktrace) const;
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(UnhandledException, Error);
   friend class Class;
+  friend class ObjectStore;
 };
 
 
 class UnwindError : public Error {
  public:
   RawString* message() const { return raw_ptr()->message_; }
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawUnwindError));
   }
@@ skipping 2988 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_