Move the canonical empty context to the VM isolate.

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 6e46e3e432ada11dfabad89172ecb730c9ddc4b2..82a12448e99074a1b1f4fab8d4d9bf9164e7b5fe 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -1127,6 +1127,7 @@ RawObject* SnapshotReader::ReadVMIsolateObject(intptr_t header_value) {
                         Object::extractor_parameter_types().raw());
   READ_VM_SINGLETON_OBJ(kExtractorParameterNames,
                         Object::extractor_parameter_names().raw());
+  READ_VM_SINGLETON_OBJ(kEmptyContextObject, Object::empty_context().raw());
   READ_VM_SINGLETON_OBJ(kEmptyContextScopeObject,
                         Object::empty_context_scope().raw());
   READ_VM_SINGLETON_OBJ(kEmptyObjectPool, Object::empty_object_pool().raw());
@@ -1369,6 +1370,7 @@ bool SnapshotWriter::HandleVMIsolateObject(RawObject* rawobj) {
                          kExtractorParameterTypes);
   WRITE_VM_SINGLETON_OBJ(Object::extractor_parameter_names().raw(),
                          kExtractorParameterNames);
+  WRITE_VM_SINGLETON_OBJ(Object::empty_context().raw(), kEmptyContextObject);
   WRITE_VM_SINGLETON_OBJ(Object::empty_context_scope().raw(),
                          kEmptyContextScopeObject);
   WRITE_VM_SINGLETON_OBJ(Object::empty_object_pool().raw(), kEmptyObjectPool);