Bug 1394841 - Add WebExt messaging to RDM tunnel. r=ochameau

WebExt messaging sends several new message types to content that should be
tunneled by RDM.

This change allows them to reach content as expected in RDM mode.

MozReview-Commit-ID: GKelgOGBUKI

--HG--
extra : rebase_source : 77288fc586efbaeb9b4c344a291c7c5f815e1a15

devtools/client/responsive.html/browser/tunnel.js

@@ -415,6 +415,8 @@ MessageManagerTunnel.prototype = {
     "Finder:",
     // Messages sent from InlineSpellChecker.jsm
     "InlineSpellChecker:",
+    // Messages sent from MessageChannel.jsm
+    "MessageChannel:",
     // Messages sent from pageinfo.js
     "PageInfo:",
     // Messages sent from printUtils.js
@@ -433,6 +435,8 @@ MessageManagerTunnel.prototype = {
     "Findbar:",
     // Messages sent to RemoteFinder.jsm
     "Finder:",
+    // Messages sent to MessageChannel.jsm
+    "MessageChannel:",
     // Messages sent to pageinfo.js
     "PageInfo:",
     // Messages sent to printUtils.js