Convert the inspector framework to use ES6 classes.

sky/framework/inspector/indexeddb-agent.sky

Index: sky/framework/inspector/indexeddb-agent.sky
diff --git a/sky/framework/inspector/indexeddb-agent.sky b/sky/framework/inspector/indexeddb-agent.sky
index 9063860f2f8b168cec188b54452f38b7e3b668e1..5d37993dfc8453c7889792c9f9cd320ec9877549 100644
--- a/sky/framework/inspector/indexeddb-agent.sky
+++ b/sky/framework/inspector/indexeddb-agent.sky
@@ -1,11 +1,14 @@
 <script>
-function IndexedDB() {
-}
+class IndexedDB {
+  constructor() {
+    Object.preventExtensions(this);
+  }
 
-// Needed to make the inspector not throw an exception.
-IndexedDB.prototype.requestDatabaseNames = function() {
-  return { "databaseNames": [] };
-};
+  // Needed to make the inspector not throw an exception.
+  requestDatabaseNames() {
+    return { "databaseNames": [] };
+  }
+}
 
 module.exports = IndexedDB;
 </script>