Add build related files.

Author: Sepand Parhami

.gitignore

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+node_modules/
+dist/

karma.conf.js

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+/**
+ * Copyright 2018 The AMP HTML Authors. All Rights Reserved.
+ *
+ * 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.
+ */
+
+module.exports = function (config) {
+  config.set({
+    frameworks: ['mocha', 'chai', 'karma-typescript'],
+    files: [
+      'src/**/*.ts',
+    ],
+    preprocessors: {
+      'src/**/*.ts': ['karma-typescript'],
+    },
+    karmaTypescriptConfig: {
+      tsconfig: './tsconfig.json',
+      compilerOptions: {
+        module: 'commonjs',
+      },
+      coverageOptions: {exclude: /.*/},
+    },
+    reporters: ['progress'],
+    port: 9876,  // karma web server port
+    colors: true,
+    logLevel: config.LOG_INFO,
+    browsers: ['Chrome', 'Firefox'],
+    autoWatch: false,
+    concurrency: Infinity,
+    customLaunchers: {
+      FirefoxHeadless: {
+        base: 'Firefox',
+        flags: ['-headless'],
+      },
+    },
+  });
+}