Replacing custom bundling with webpack2.

external/webpack/block-require.js

@@ -0,0 +1,50 @@
+/* Copyright 2017 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/* eslint-env node */
+
+'use strict';
+
+function isPDFJSDevCheck(test) {
+  // Is it something like `typeof __pdfjsdev_webpack__ === 'undefined'`?
+  return test.type === 'BinaryExpression' &&
+         (test.operator === '===' || test.operator === '!==' ||
+          test.operator === '==' || test.operator === '!=') &&
+         test.left.type === 'UnaryExpression' &&
+         test.left.operator === 'typeof' &&
+         test.left.argument.type === 'Identifier' &&
+         test.left.argument.name === '__pdfjsdev_webpack__' &&
+         test.right.type === 'Literal' && test.right.value === 'undefined';
+}
+
+function isPDFJSDevEnabled(test) {
+  return test.operator[0] === '!';
+}
+
+function BlockRequirePlugin() {}
+
+BlockRequirePlugin.prototype.apply = function(compiler) {
+  compiler.plugin('compilation', function(compilation, data) {
+    data.normalModuleFactory.plugin('parser', function (parser, options) {
+      parser.plugin('statement if', function (ifNode) {
+        if (isPDFJSDevCheck(ifNode.test)) {
+          return isPDFJSDevEnabled(ifNode.test);
+        }
+        return undefined;
+      });
+    });
+  });
+};
+
+module.exports = BlockRequirePlugin;