Bug 1329731 - Add moz-extension to the principals immune to script policy. r=bholley

MozReview-Commit-ID: FAn2Cq5Lz5O

--HG--
extra : rebase_source : 8d89707f91747946d98e473983345d6a5857ea89

js/xpconnect/src/XPCJSContext.cpp

@@ -347,6 +347,15 @@ PrincipalImmuneToScriptPolicy(nsIPrincipal* aPrincipal)
     nsCOMPtr<nsIURI> principalURI;
     aPrincipal->GetURI(getter_AddRefs(principalURI));
     MOZ_ASSERT(principalURI);
+
+    // WebExtension principals gets a free pass.
+    nsString addonId;
+    aPrincipal->GetAddonId(addonId);
+    bool isWebExtension = !addonId.IsEmpty();
+    if (isWebExtension) {
+        return true;
+    }
+
     bool isAbout;
     nsresult rv = principalURI->SchemeIs("about", &isAbout);
     if (NS_SUCCEEDED(rv) && isAbout) {