Factor out handling of mixed objects preprocessing after migration

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 7c9b4f8052ff8c00d560baef20724d6ef1ec835c..d20cd5c83045b16e716407e9cacda5c50b5069c0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1437,6 +1437,10 @@ class HeapObject: public Object {
   // look like pointers to heap objects.
   inline bool MayContainRawValues();
 
+  // Returns true if this heap object may contain both raw values and
+  // tagged pointers.
+  inline bool MayContainMixedValues();

[Igor Sheludko, 2015/05/13 12:22:59]

Does it make sense to merge two MayContain..() methods into a new one returning
enum? 

+
   // Given a heap object's map pointer, returns the heap size in bytes
   // Useful when the map pointer field is used for other purposes.
   // GC internal.