Add a version number for full and script snapshots.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 39523)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -4882,10 +4882,10 @@
                         snapshot->length(),
                         snapshot->kind(),
                         isolate);
-  const Object& tmp = Object::Handle(isolate, reader.ReadObject());
+  const Object& tmp = Object::Handle(isolate, reader.ReadScriptSnapshot());
   if (!tmp.IsLibrary()) {
-    return Api::NewError("%s: Unable to deserialize snapshot correctly.",
-                         CURRENT_FUNC);
+    ASSERT(tmp.IsError());

[Ivan Posva, 2014/08/26 23:52:42]

If this is an error we should just return the error object. Otherwise we should
create a new error object as previously.

[siva, 2014/08/27 18:25:07]

Removed this error and change ReadScriptSnapshot to return a library object or
an error object.

+    return Api::NewHandle(isolate, tmp.raw());
   }
   library ^= tmp.raw();
   library.set_debuggable(true);