Remove assumption from the heap verifier that objects occupy a narrow range of the address space.

runtime/vm/heap.h

Index: runtime/vm/heap.h
diff --git a/runtime/vm/heap.h b/runtime/vm/heap.h
index 63f35d877c036b5d41e2cc8916d5279dd24ef5e1..deae0a0bfed37e580b6ab50d0aa6a20b325667f0 100644
--- a/runtime/vm/heap.h
+++ b/runtime/vm/heap.h
@@ -166,7 +166,8 @@ class Heap {
 
   intptr_t Collections(Space space) const;
 
-  ObjectSet* CreateAllocatedObjectSet(MarkExpectation mark_expectation) const;
+  ObjectSet* CreateAllocatedObjectSet(Zone* zone,
+                                      MarkExpectation mark_expectation) const;
 
   static const char* GCReasonToString(GCReason gc_reason);
 
@@ -329,10 +330,7 @@ class Heap {
   bool BeginOldSpaceGC(Thread* thread);
   void EndOldSpaceGC();
 
-  // If this heap is non-empty, updates start and end to the smallest range that
-  // contains both the original [start, end) and the [lowest, highest) addresses
-  // of this heap.
-  void GetMergedAddressRange(uword* start, uword* end) const;
+  void AddRegionsToObjectSet(ObjectSet* set) const;
 
   Isolate* isolate_;