Adding Angular and dependent packages for testing

third_party/pkg/angular/playback_middleware/lib/playback.js

+
+function playback(opts) {
+  var records = [];
+  var seen = {};
+
+  function record(key, data) {
+    if (seen[key]) return;
+    records.push({key: key, data: data});
+    seen[key] = true;
+  }
+
+  function playback() {
+    var lines = [
+        'library angular.core.service.playback_data;',
+        '',
+        'import "dart:convert";',
+        '',
+        '// Auto-generated by record-playback',
+        '',
+        'Map<String, String> playbackData = {'
+    ];
+
+    records.forEach(function(r) {
+      var keyString = JSON.stringify(r.key).replace(/\$/g, '\\$');
+      var valueString = JSON.stringify(r.data).replace(/\$/g, '\\$');
+      lines.push('  ' + keyString + ': JSON.decode(' + valueString + '),');
+    });
+
+    lines.push('};');
+
+    return lines.join('\n');
+  }
+
+  return {
+    record: record,
+    playback: playback
+  }
+}
+
+module.exports = {
+  playback: playback
+};