Issue 5316 - Adds supported filter types export value to requestBlocker

lib/requestBlocker.js

Index: lib/requestBlocker.js
===================================================================
--- a/lib/requestBlocker.js
+++ b/lib/requestBlocker.js
@@ -48,16 +48,23 @@
   // Treat navigator.sendBeacon() the same as <a ping>, it's essentially the
   // same concept - merely generalized.
   yield ["beacon", "PING"];
 
   // Treat <img srcset> and <picture> the same as other images.
   yield ["imageset", "IMAGE"];
 }());
 
+// Expose supported resource types for devtools panel

[Jon Sonesen, 2017/08/21 15:33:07]

I think this comment could be improved but not sure if it is that important,
since it seems clear what the code is doing.

[Sebastian Noack, 2017/08/22 09:47:28]

Yeah, I'd rather just remove that comment.

[Jon Sonesen, 2017/09/01 08:09:06]

Acknowledged.

+exports.filterTypes = new Set(function*()
+{
+  for (let type in chrome.webRequest.ResourceType)

[Sebastian Noack, 2017/08/22 09:47:28]

webRequest.ResourceType doesn't exist in Microsoft Edge. However, neither does
the devtools panel, so the value of filterTypes is irrelevant there, but we
still have to detect whether ResourceType exists in order to prevent this script
from throwing an error on Microsoft Edge.

[Jon Sonesen, 2017/09/01 08:09:06]

Cool, can I just return if !(chrome.webRequest.ResourceType)?

[Sebastian Noack, 2017/09/05 18:08:10]

Yes, that will do.

+    yield resourceTypes.get(chrome.webRequest.ResourceType[type]) || "OTHER";

[Sebastian Noack, 2017/08/22 09:47:28]

There are some filter types which we need to hard-code here, in addition to
those which we can detect based on webRequest.ResourceType. These are:

* WEBSOCKET (supported through a workaround if not in ResourceType)
* WEBRTC (supported through a workaround)
* POPUP (non-request type)
* ELEMHIDE (non-request type)

[Jon Sonesen, 2017/09/01 08:09:06]

Cool, does it make sense to just add yields with each type after the iteration?

[Sebastian Noack, 2017/09/05 18:08:10]

Yes, I think this is the simplest approach.

+}());
+
 function onBeforeRequestAsync(page, url, type, docDomain,
                               thirdParty, sitekey,
                               specificOnly, filter)
 {
   if (filter)
     FilterNotifier.emit("filter.hitCount", filter, 0, 0, page);
 
   if (devtools)