Revert "Moves the top_ and end_ words of the Scavenger into mutator thread."

runtime/vm/scavenger_test.cc

Index: runtime/vm/scavenger_test.cc
diff --git a/runtime/vm/scavenger_test.cc b/runtime/vm/scavenger_test.cc
index 4f1622282b094a113cdd157efc4d59dec9ad4597..cd8d61060b8a932bb51f5ee3af77b6c0c6f62c9b 100644
--- a/runtime/vm/scavenger_test.cc
+++ b/runtime/vm/scavenger_test.cc
@@ -35,4 +35,19 @@ class FailingFindObjectVisitor : public FindObjectVisitor {
   }
 };
 
+TEST_CASE(ZeroSizeScavenger) {
+  Scavenger* scavenger = new Scavenger(NULL, 0, kNewObjectAlignmentOffset);
+  EXPECT(!scavenger->Contains(reinterpret_cast<uword>(&scavenger)));
+  EXPECT_EQ(0, scavenger->UsedInWords());
+  EXPECT_EQ(0, scavenger->CapacityInWords());
+  EXPECT_EQ(static_cast<uword>(0), scavenger->TryAllocate(kObjectAlignment));
+  FailingObjectVisitor obj_visitor;
+  scavenger->VisitObjects(&obj_visitor);
+  FailingObjectPointerVisitor ptr_visitor;
+  scavenger->VisitObjectPointers(&ptr_visitor);
+  FailingFindObjectVisitor find_visitor;
+  scavenger->FindObject(&find_visitor);
+  delete scavenger;
+}
+
 }  // namespace dart