Make core snapshot word-size portable again.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 143cf9e409ac4647df55b2b7b58f3ad3ea61cb2e..768c8749fde6e7e4705d51e728f5e059db9454a2 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1326,6 +1326,7 @@ class Class : public Object {
   void DisableAllocationStub() const;
 
   RawArray* constants() const;
+  void set_constants(const Array& value) const;
 
   intptr_t FindInvocationDispatcherFunctionIndex(const Function& needle) const;
   RawFunction* InvocationDispatcherFunctionFromIndex(intptr_t idx) const;
@@ -1459,8 +1460,6 @@ class Class : public Object {
   RawString* GenerateUserVisibleName() const;
   void set_state_bits(intptr_t bits) const;
 
-  void set_constants(const Array& value) const;
-
   void set_canonical_type(const Type& value) const;
   RawType* canonical_type() const;