Bug 32411: Letterboxing, exempt view-source: URIs.

toolkit/components/resistfingerprinting/RFPHelper.sys.mjs

@@ -387,6 +387,8 @@ class _RFPHelper {
       contentPrincipal.isSystemPrincipal ||
       // ... about: URIs EXCEPT about:blank
       (currentURI.schemeIs("about") && currentURI.filePath !== "blank") ||
+      // ... source code
+      currentURI.schemeIs("view-source") ||
       // ... browser extensions
       contentPrincipal.addonPolicy
     );