Bug 1321509 - remove references to Array.slice in addon-sdk util/object;r=zer0

MozReview-Commit-ID: 8HCwdqy4kwl

--HG--
extra : rebase_source : e6712c8ec0e18427151e1db53769efea35fd5106

addon-sdk/source/lib/sdk/util/object.js

@@ -9,6 +9,10 @@ module.metadata = {
 
 const { flatten } = require('./array');
 
+// Create a shortcut for Array.prototype.slice.call().
+const unbind = Function.call.bind(Function.bind, Function.call);
+const slice = unbind(Array.prototype.slice);
+
 /**
  * Merges all the properties of all arguments into first argument. If two or
  * more argument objects have own properties with the same name, the property
@@ -34,7 +38,7 @@ function merge(source) {
   // `Boolean` converts the first parameter to a boolean value. Any object is
   // converted to `true` where `null` and `undefined` becames `false`. Therefore
   // the `filter` method will keep only objects that are defined and not null.
-  Array.slice(arguments, 1).filter(Boolean).forEach(function onEach(properties) {
+  slice(arguments, 1).filter(Boolean).forEach(function onEach(properties) {
     getOwnPropertyIdentifiers(properties).forEach(function(name) {
       descriptor[name] = Object.getOwnPropertyDescriptor(properties, name);
     });
@@ -50,7 +54,7 @@ exports.merge = merge;
  * `merge(Object.create(source1), source2, source3)`.
  */
 function extend(source) {
-  let rest = Array.slice(arguments, 1);
+  let rest = slice(arguments, 1);
   rest.unshift(Object.create(source));
   return merge.apply(null, rest);
 }
@@ -72,7 +76,7 @@ exports.each = each;
  * merging XPCOM objects
  */
 function safeMerge(source) {
-  Array.slice(arguments, 1).forEach(function onEach (obj) {
+  slice(arguments, 1).forEach(function onEach (obj) {
     for (let prop in obj) source[prop] = obj[prop];
   });
   return source;