Weird issue when referencing `document` in callback of will-destroy

I'm not sure how/if this is really related to the modifiers, but I haven't been able to reproduce it without them. I believe it's some kind of interaction between babel/decorators/modifiers.

Apparently if in the callback passed to `{{will-destroy}}` I use the global `document` without having referenced it elsewhere, the compilation blows badly:

```
ReferenceError: document is not defined
at BasicDropdownTrigger.removeGlobalHandlers (/var/folders/bt/62lj_mr106zbk82m8kl772b00000gn/T/broccoli-9932Xc3l4ZKiotlD/out-271-broccoli_merge_trees/assets/addon-tree-output/ember-basic-dropdown/components/basic-dropdown-trigger.js:140:1)
at Object.destroyModifier (/var/folders/bt/62lj_mr106zbk82m8kl772b00000gn/T/broccoli-9932Xc3l4ZKiotlD/out-271-broccoli_merge_trees/assets/addon-tree-output/@ember/render-modifiers/modifiers/will-destroy.js:26:1)
at CustomModifierState.destroy (/var/folders/bt/62lj_mr106zbk82m8kl772b00000gn/T/broccoli-9932Xc3l4ZKiotlD/out-271-broccoli_merge_trees/assets/vendor/ember-modifier-manager-polyfill.js:58:1)
at SimpleBlockTracker.destroy (/var/folders/bt/62lj_mr106zbk82m8kl772b00000gn/T/broccoli-9932Xc3l4ZKiotlD/out-271-broccoli_merge_trees/assets/@glimmer/runtime.js:2411:1)
at UpdatableBlockTracker.destroy (/var/folders/bt/62lj_mr106zbk82m8kl772b00000gn/T/broccoli-9932Xc3l4ZKiotlD/out-271-broccoli_merge_trees/assets/@glimmer/runtime.js:2411:1)
```

The reproduction can be this PR: https://github.com/cibernox/ember-basic-dropdown/pull/449

If (this line)[https://github.com/cibernox/ember-basic-dropdown/pull/449/files#diff-e8b1232b23cd9aba9a4b4c3f74b118fcR18] referencing the global document is removed the code fails to compile.