Check for class id overflow to exit rather than crash.

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 673 matching lines @@
            (!Utils::IsAligned((value * kWordSize), kObjectAlignment) &&
             ((value + 1) == raw_ptr()->instance_size_in_words_)));
     raw_ptr()->next_field_offset_in_words_ = value;
   }
 
   cpp_vtable handle_vtable() const { return raw_ptr()->handle_vtable_; }
   void set_handle_vtable(cpp_vtable value) const {
     raw_ptr()->handle_vtable_ = value;
   }
 
+  static bool is_valid_id(intptr_t value) {
+    return RawObject::ClassIdTag::is_valid(value);
+  }
   intptr_t id() const { return raw_ptr()->id_; }
   void set_id(intptr_t value) const {
+    ASSERT(is_valid_id(value));
     raw_ptr()->id_ = value;
   }
 
   RawString* Name() const;
   RawString* UserVisibleName() const;
 
   virtual RawString* DictionaryName() const { return Name(); }
 
   RawScript* script() const { return raw_ptr()->script_; }
   void set_script(const Script& value) const;
@@ skipping 6124 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_