Use eslint-env "shared-node-browser" for shared handlebars code

lib/.eslintrc.js

@@ -1,6 +1,8 @@
 module.exports = {
   env: {
-    // Handlebars should run natively in the browser
-    node: false
+    // Handlebars not use node or browser-specific apis
+    'shared-node-browser': true,
+    node: false,
+    browser: false
   }
 };

lib/handlebars/compiler/code-gen.js

@@ -1,4 +1,4 @@
-/* global define */
+/* global define, require */
 import { isArray } from '../utils';
 
 let SourceNode;
@@ -8,7 +8,7 @@ try {
   if (typeof define !== 'function' || !define.amd) {
     // We don't support this in AMD environments. For these environments, we assume that
     // they are running on the browser and thus have no need for the source-map library.
-    let SourceMap = require('source-map'); // eslint-disable-line no-undef
+    let SourceMap = require('source-map');
     SourceNode = SourceMap.SourceNode;
   }
 } catch (err) {

lib/handlebars/no-conflict.js

@@ -1,6 +1,7 @@
+/* global global, window */
 export default function(Handlebars) {
   /* istanbul ignore next */
-  let root = typeof global !== 'undefined' ? global : window, // eslint-disable-line no-undef
+  let root = typeof global !== 'undefined' ? global : window,
     $Handlebars = root.Handlebars;
   /* istanbul ignore next */
   Handlebars.noConflict = function() {