Fix binding style attribute warning in paper-backdrop (#663)

CHANGELOG.md

@@ -27,6 +27,7 @@ Contributions and pull requests are always welcome. Contributors may often be fo
 - [8a5e370](https://github.com/miguelcobain/ember-paper/commit/8a5e370fe18829db5dae7e89f7744848dca186cf) update angular material to `v1.0.9`
 - [10fddd9](https://github.com/miguelcobain/ember-paper/commit/10fddd9027f28c1bdfdab903d067377211536d76) Enhance customizability paper-{form, input, radio-group}
 - [a86bb64](https://github.com/miguelcobain/ember-paper/commit/a86bb6422d5f6f458dbc6b1eda123fcf136f9f0a) fix paper-slider on iOS devices
+- [#663](https://github.com/miguelcobain/ember-paper/pull/663) Fix binding style attribute warning in paper-backdrop
 
 ### 1.0.0-alpha.16 (February 14, 2017) <--- forever alone
 - [#636](https://github.com/miguelcobain/ember-paper/pull/636) Consuming apps can now specify `ENV['ember-paper'].insertFontLinks` to prevent the insertion of google fonts links in the head tag. This is especially useful if you want to include your own fonts.

addon/components/paper-backdrop.js

@@ -4,7 +4,7 @@
 import Ember from 'ember';
 import TransitionMixin from 'ember-css-transitions/mixins/transition-mixin';
 
-const { Component, computed } = Ember;
+const { Component, computed, String: { htmlSafe } } = Ember;
 
 /**
  * @class PaperBackdrop
@@ -23,7 +23,7 @@ export default Component.extend(TransitionMixin, {
   shouldTransition: computed.bool('opaque'),
 
   backdropStyle: computed('fixed', function() {
-    return this.get('fixed') ? 'position:fixed;' : null;
+    return this.get('fixed') ? htmlSafe('position:fixed;') : null;
   }),
 
   addDestroyedElementClone(original, clone) {