get and set work with global paths when emulating 1.0

When `ACCESSORS` is set to `"0.9"` or `"0.9-dotted-properties"`,
 * `Em.getPath('Foo.bar')` returns `window.Foo.bar`
 * `Em.setPath('Foo.bar', 'baz')` sets `window.Foo.bar` to `"baz"`

When `ACCESSORS` is set to `"1.0-no-warn"` or `"1.0"`, the `getPath` and
`setPath` versions continued to work, but `get` and `set` didn't work
with global paths. Now they do, just like in Ember 1.0.
typo in scripts/browser_tests
move backported view state tests to ember-viewstates package

They were failing in the ember-states package because `Ember.ViewState`
wasn't defined when running in isolation.