Fix tests for Handlebars 2.0

ember-source 1.9.0 depends on Handlebars 2.0.
The precompiled code from this version is not compatible with Handlebars 1.3.0.

So I fixed test code with compatibility.
But a bit weak than previous revision...

If it is not acceptable, I'll try to switch using `if Ember::VERSION =~ /^1\.10/` or similar.