1 files changed, 10 insertions, 0 deletions
diff --git a/toolkit/modules/addons/WebRequestContent.js b/toolkit/modules/addons/WebRequestContent.js
index 219675e5b..f044a1cd4 100644
--- a/toolkit/modules/addons/WebRequestContent.js
+++ b/toolkit/modules/addons/WebRequestContent.js
@@ -80,6 +80,16 @@ var ContentPolicy = {
 
   shouldLoad(policyType, contentLocation, requestOrigin,
              node, mimeTypeGuess, extra, requestPrincipal) {
+
+    // Loads of TYPE_DOCUMENT and TYPE_SUBDOCUMENT perform a ConPol check
+    // within docshell as well as within the ContentSecurityManager. To avoid
+    // duplicate evaluations we ignore ConPol checks performed within docShell.
+    if (extra instanceof Ci.nsISupportsString) {
+      if (extra.data === "conPolCheckFromDocShell") {
+        return Ci.nsIContentPolicy.ACCEPT;
+      }
+    }
+
     if (requestPrincipal &&
         Services.scriptSecurityManager.isSystemPrincipal(requestPrincipal)) {
       return Ci.nsIContentPolicy.ACCEPT;