Convert the inspector framework to use ES6 classes.

sky/framework/inspector/console-agent.sky

Index: sky/framework/inspector/console-agent.sky
diff --git a/sky/framework/inspector/console-agent.sky b/sky/framework/inspector/console-agent.sky
index 58240d81eb768afdda1a44f1a369293fd2da1c19..f8628568fc5bb03e3900de218c7906a0e93ac7d4 100644
--- a/sky/framework/inspector/console-agent.sky
+++ b/sky/framework/inspector/console-agent.sky
@@ -1,12 +1,15 @@
 <script>
-function ConsoleAgent() {
-}
+class ConsoleAgent {
+  constructor() {
+    Object.preventExtensions(this);
+  }
 
-ConsoleAgent.prototype.enable = function() {
-  return {
-    result: true,
-  };
-};
+  enable() {
+    return {
+      result: true,
+    };
+  }
+}
 
 module.exports = ConsoleAgent;
 </script>