Bug 1398601 - Fix devtools browser_gcli_async test r=tromey

This test has encoding issues that accidently worked before. The
mockCommands.js file was loaded under two different encodings, but
previously the cache would always return the first encoding.

MozReview-Commit-ID: GE9BFy2RkqL

--HG--
extra : rebase_source : 28a7cb0c889a6a17800cb86432c0d3f464b37782

devtools/client/commandline/test/browser_gcli_async.js

@@ -52,7 +52,7 @@ exports.testBasic = function (options) {
         current: "hello",
         status: "ERROR",
         predictions: [
-          "Shalom", "Namasté", "Hallo", "Dydd-da", "Chào", "Hej",
+          "Shalom", "Namast\u{00E9}", "Hallo", "Dydd-da", "Ch\u{00E0}o", "Hej",
           "Saluton", "Sawubona"
         ],
         unassigned: [ ],
@@ -74,7 +74,7 @@ exports.testBasic = function (options) {
         cursor: 8,
         current: "hello",
         status: "ERROR",
-        predictions: [ "Shalom", "Saluton", "Sawubona", "Namasté" ],
+        predictions: [ "Shalom", "Saluton", "Sawubona", "Namast\u{00E9}" ],
         unassigned: [ ],
         args: {
           command: { name: "tsslow" },

devtools/client/commandline/test/head.js

@@ -17,7 +17,7 @@ var flags = require("devtools/shared/flags");
 // Import the GCLI test helper
 var testDir = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
 Services.scriptloader.loadSubScript(testDir + "/helpers.js", this);
-Services.scriptloader.loadSubScript(testDir + "/mockCommands.js", this);
+Services.scriptloader.loadSubScript(testDir + "/mockCommands.js", this, "UTF-8");
 
 flags.testing = true;
 SimpleTest.registerCleanupFunction(() => {