Ensure that hash for a symbol is not set to 0 when it is made external.

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 5371 matching lines @@
 
   intptr_t Hash() const {
     intptr_t result = Smi::Value(raw_ptr()->hash_);
     if (result != 0) {
       return result;
     }
     result = String::Hash(*this, 0, this->Length());
     this->SetHash(result);
     return result;
   }
+  bool HasHash() const {
+    ASSERT(Smi::New(0) == NULL);
+    return (raw_ptr()->hash_ != NULL);
+  }
 
   static intptr_t hash_offset() { return OFFSET_OF(RawString, hash_); }
   static intptr_t Hash(const String& str, intptr_t begin_index, intptr_t len);
   static intptr_t HashLatin1(const uint8_t* characters, intptr_t len);
   static intptr_t Hash(const uint16_t* characters, intptr_t len);
   static intptr_t Hash(const int32_t* characters, intptr_t len);
   static intptr_t HashRawSymbol(const RawString* symbol) {
     ASSERT(symbol->IsCanonical());
     intptr_t result = Smi::Value(symbol->ptr()->hash_);
     ASSERT(result != 0);
@@ skipping 193 matching lines @@
                           intptr_t end,
                           double* result);
 
  protected:
   // These two operate on an array of Latin-1 encoded characters.
   // They are protected to avoid mistaking Latin-1 for UTF-8, but used
   // by friendly templated code (e.g., Symbols).
   bool Equals(const uint8_t* characters, intptr_t len) const;
   static intptr_t Hash(const uint8_t* characters, intptr_t len);
 
-  bool HasHash() const {
-    ASSERT(Smi::New(0) == NULL);
-    return (raw_ptr()->hash_ != NULL);
-  }
-
   void SetLength(intptr_t value) const {
     // This is only safe because we create a new Smi, which does not cause
     // heap allocation.
     raw_ptr()->length_ = Smi::New(value);
   }
 
   void SetHash(intptr_t value) const {
     // This is only safe because we create a new Smi, which does not cause
     // heap allocation.
     raw_ptr()->hash_ = Smi::New(value);
@@ skipping 1696 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_