Issue 3251 - Simplify messaging from child scripts to parent

lib/child/contentPolicy.js

Index: lib/child/contentPolicy.js
===================================================================
--- a/lib/child/contentPolicy.js
+++ b/lib/child/contentPolicy.js
@@ -65,20 +65,20 @@ let types = new Map();
 function shouldAllow(window, node, contentType, location)
 {
   let response = sendSyncMessage("AdblockPlus:ShouldAllow", {
     contentType: contentType,
     location: location,
     frames: getFrames(window),
     isPrivate: isPrivate(window)
   });
-  if (response.length == 0)
+  if (typeof response == "undefined")
     return true;
 
-  let {allow, collapse, hits} = response[0];
+  let {allow, collapse, hits} = response;
   for (let {frameIndex, contentType, docDomain, thirdParty, location, filter} of hits)
   {
     let context = node;
     if (typeof frameIndex == "number")
     {
       context = window;
       for (let i = 0; i < frameIndex; i++)
         context = context.parent;
@@ -311,21 +311,17 @@ function schedulePostProcess(/**Element*
 }
 
 /**
  * Processes nodes scheduled for post-processing (typically hides them).
  */
 function postProcessNodes()
 {
   if (!collapsedClass)
-  {
-    let response = sendSyncMessage("AdblockPlus:GetCollapsedClass");
-    if (response.length)
-      collapsedClass = response[0];
-  }
+    collapsedClass = sendSyncMessage("AdblockPlus:GetCollapsedClass");
 
   let nodes = scheduledNodes;
   scheduledNodes = null;
 
   if (!collapsedClass)
     return;
 
   for (let node of nodes)