Add Mozilla's Criteo shim script (#33)

Some websites display a "Please disable your ad blocker" wall, or
otherwise break when the criteo.net/js/ld/publishertag.js script is
blocked. Let's instead redirect that request to Mozilla's shim
script[1].

1 - https://searchfox.org/mozilla-central/source/browser/extensions/webcompat/shims/criteo.js

mapping.json

@@ -10,6 +10,9 @@
         { "regexRule": "chartbeat\\.com\\/chartbeat\\.js", "surrogate": "chartbeat.js" },
         { "regexRule": "chartbeat\\.com\\/js\\/chartbeat\\.js", "surrogate": "chartbeat.js" }
     ],
+    "criteo.net": [
+        { "regexRule": "criteo\\.net\\/js\\/ld\\/publishertag\\.js", "surrogate": "criteo.js" }
+    ],
     "doubleclick.net": [
         { "regexRule": "doubleclick\\.net\\/instream\\/ad_status\\.js", "surrogate": "ad_status.js" },
         { "regexRule": "doubleclick\\.net\\/tag\\/js\\/gpt\\.js", "surrogate": "gpt.js" }

surrogates/criteo.js

@@ -0,0 +1,69 @@
+"use strict";
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Based on https://searchfox.org/mozilla-central/source/browser/extensions/webcompat/shims/criteo.js
+
+/* eslint indent: ["error", 2], quotes: ["error", "double"],
+   comma-dangle: ["error", "only-multiline"], space-before-function-paren: ["error", "never"] */
+
+/**
+ * Bug 1713720 - Shim Criteo
+ *
+ * Sites relying on window.Criteo to be loaded can experience
+ * breakage if it is blocked. Stubbing out the API in a shim can
+ * mitigate this breakage.
+ */
+
+if (!(window.Criteo && window.Criteo.CallRTA)) {
+  window.Criteo = {
+    CallRTA() {},
+    ComputeStandaloneDFPTargeting() {},
+    DisplayAcceptableAdIfAdblocked() {},
+    DisplayAd() {},
+    GetBids() {},
+    GetBidsForAdUnit() {},
+    Passback: {
+      RequestBids() {},
+      RenderAd() {},
+    },
+    PubTag: {
+      Adapters: {
+        AMP() {},
+        Prebid() {},
+      },
+      Context: {
+        GetIdfs() {},
+        SetIdfs() {},
+      },
+      DirectBidding: {
+        DirectBiddingEvent() {},
+        DirectBiddingSlot() {},
+        DirectBiddingUrlBuilder() {},
+        Size() {},
+      },
+      RTA: {
+        DefaultCrtgContentName: "crtg_content",
+        DefaultCrtgRtaCookieName: "crtg_rta",
+      },
+    },
+    RenderAd() {},
+    RequestBids() {},
+    RequestBidsOnGoogleTagSlots() {},
+    SetCCPAExplicitOptOut() {},
+    SetCeh() {},
+    SetDFPKeyValueTargeting() {},
+    SetLineItemRanges() {},
+    SetPublisherExt() {},
+    SetSlotsExt() {},
+    SetTargeting() {},
+    SetUserExt() {},
+    events: {
+      push() {},
+    },
+    passbackEvents: [],
+    usePrebidEvents: true,
+  };
+}