Add lint checks for curly braces and return values in Array callbacks

Checking for return values in Array callbacks found several incorrect
uses of Array.map() where Array.forEach() should have been used.

.eslintrc

@@ -11,7 +11,9 @@
     "Promise": false,
   },
   "rules": {
+    "array-callback-return": "error",
     "block-scoped-var": "error",
+    "curly": "error",
     "eqeqeq": "error",
     "no-console": [
       "error",

gulpfile.js

@@ -121,7 +121,7 @@ gulp.task('build-app-js', ['build-vendor-js'], function () {
 });
 
 gulp.task('watch-app-js', ['build-vendor-js'], function () {
-  appBundleConfigs.map(function (config) {
+  appBundleConfigs.forEach(function (config) {
     createBundle(config, {watch: true});
   });
 });

h/static/scripts/build-thread.js

@@ -121,7 +121,7 @@ function threadAnnotations(annotations) {
   // Collect the set of threads which have no parent as
   // children of the thread root
   var roots = [];
-  Object.keys(threads).map(function (id) {
+  Object.keys(threads).forEach(function (id) {
     if (!threads[id].parent) {
       // Top-level threads are collapsed by default
       threads[id].collapsed = true;

h/static/scripts/frame-rpc.js

 'use strict';
 
+/* eslint curly: "off" */
+
 /** This software is released under the MIT license:
 
   Permission is hereby granted, free of charge, to any person obtaining a copy

scripts/decaf/decaf.js

@@ -81,10 +81,9 @@ function stripUnnecessaryReturns(js) {
       for (var i=0; i < stripReturnPatterns.length; i++) {
         if (remainder.match(stripReturnPatterns[i])) {
           return remainder;
-        } else {
-          return remainder;
         }
       }
+      return line;
     } else {
       return line;
     }