Configurable "lazy_load" capability (see https://github.com/whatwg/html/issues/5250).

src/_locales/en/messages.json

@@ -572,6 +572,9 @@
   "cap_noscript": {
     "message": "noscript"
   },
+  "cap_lazy_load": {
+    "message": "lazy load"
+  },
   "cap_unchecked_css": {
     "message": "unrestricted CSS"
   },

src/bg/LifeCycle.js

@@ -324,6 +324,11 @@ var LifeCycle = (() => {
           ns.openOptionsPage({tab: 2, focus: "#opt-vintageTheme", hilite: "#sect-themes"});
         })();
       }
+
+      if (Ver.is(previousVersion, "<=", "11.4.35rc2")) {
+        // add the lazy_load capability to any preset which already has the script capability
+        await configureNewCap("lazy_load", ["DEFAULT", "TRUSTED", "CUSTOM"], caps => caps.has("script"));
+      }
     },
 
     async onUpdateAvailable(details) {

src/content/content.js

@@ -183,6 +183,43 @@ ns.on("capabilities", () => {
       allowed: ns.canScript
     });
 
+  if (!ns.allows("lazy_load")) {
+    // Force loading attributes to "eager", since CSP-based script blocking
+    // does not disable lazy loading as it should to address the privacy
+    // concerns mentioned in the specification.
+    // See https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42805
+
+    const toEager = el => el.setAttribute("loading", "eager");
+    const toEagerAll = parent => [... parent.querySelectorAll("[loading=lazy]")].forEach(toEager);
+
+    toEagerAll(document);
+    if (document.readyState === "loading") {
+
+      const observer = new MutationObserver(records => {
+        for (const r of records) {
+          console.log(r);
+          switch(r.type) {
+            case "attributes":
+              if (r.attributeName === "loading") {
+                toEager(r.target);
+              }
+              break;
+            case "subtree":
+              toEagerAll(r.target);
+              break;
+          }
+
+        }
+      });
+
+      observer.observe(document.documentElement, {subtree: true, attributeFilter: ["loading"]});
+      addEventListener("DOMContentLoaded", e => {
+        toEagerAll(document);
+        observer.disconnect();
+      });
+    }
+  }
+
   if (!ns.allows("unchecked_css")) {
     // protection against CSS PP0 (https://orenlab.sise.bgu.ac.il/p/PP0)
 

src/content/onScriptDisabled.js

@@ -46,43 +46,6 @@ function onScriptDisabled() {
     }
   }
 
-  {
-    // Force loading attributes to "eager", since CSP-based script blocking
-    // does not disable lazy loading as it should to address the privacy
-    // concerns mentioned in the specification.
-    // See https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42805
-
-    const toEager = el => el.setAttribute("loading", "eager");
-    const toEagerAll = parent => [... parent.querySelectorAll("[loading=lazy]")].forEach(toEager);
-
-    toEagerAll(document);
-    if (document.readyState === "loading") {
-
-      const observer = new MutationObserver(records => {
-        for (const r of records) {
-          console.log(r);
-          switch(r.type) {
-            case "attributes":
-              if (r.attributeName === "loading") {
-                toEager(r.target);
-              }
-              break;
-            case "subtree":
-              toEagerAll(r.target);
-              break;
-          }
-
-        }
-      });
-
-      observer.observe(document.documentElement, {subtree: true, attributeFilter: ["loading"]});
-      addEventListener("DOMContentLoaded", e => {
-        toEagerAll(document);
-        observer.disconnect();
-      });
-    }
-  }
-
   let eraser = {
     tapped: null,
     delKey: false,

src/nscl

@@ -1 +1 @@
-Subproject commit c59937693d3fd772add35e918eb90744ff55d148
+Subproject commit 9cef1fb442641dbf8e44ad70deb990828d5b5de3