Merge pull request #1526 from zombie/1026187-proto-warning

Bug 1026187 - avoid setting __proto__ r=@ZER0

lib/sdk/test/harness.js

@@ -18,6 +18,7 @@ const system = require("../system");
 const memory = require('../deprecated/memory');
 const { gc: gcPromise } = require('./memory');
 const { defer } = require('../core/promise');
+const { extend } = require('../core/heritage');
 
 // Trick manifest builder to make it think we need these modules ?
 const unit = require("../deprecated/unit-test");
@@ -453,7 +454,7 @@ var consoleListener = {
 };
 
 function TestRunnerConsole(base, options) {
-  this.__proto__ = {
+  let proto = extend(base, {
     errorsLogged: 0,
     warn: function warn() {
       this.errorsLogged++;
@@ -470,8 +471,8 @@ function TestRunnerConsole(base, options) {
         if (first == "pass:")
           print(".");
     },
-    __proto__: base
-  };
+  });
+  return Object.create(proto);
 }
 
 function stringify(arg) {