Add read only handles for the following predefined symbols

vm/assembler_x64.cc

Index: vm/assembler_x64.cc
===================================================================
--- vm/assembler_x64.cc	(revision 15918)
+++ vm/assembler_x64.cc	(working copy)
@@ -1652,7 +1652,7 @@
   if (object.IsSmi() || object.IsNull()) {
     movq(dst, Immediate(reinterpret_cast<int64_t>(object.raw())));
   } else {
-    ASSERT(object.IsZoneHandle());
+    ASSERT(object.IsPredefinedHandle() || object.IsZoneHandle());
     ASSERT(object.IsOld());
     AssemblerBuffer::EnsureCapacity ensured(&buffer_);
     EmitRegisterREX(dst, REX_W);
@@ -1666,7 +1666,7 @@
   if (object.IsSmi() || object.IsNull()) {
     movq(dst, Immediate(reinterpret_cast<int64_t>(object.raw())));
   } else {
-    ASSERT(object.IsZoneHandle());
+    ASSERT(object.IsPredefinedHandle() || object.IsZoneHandle());
     ASSERT(object.IsOld());
     LoadObject(TMP, object);
     movq(dst, TMP);