--- a/caps/ContentPrincipal.cpp
+++ b/caps/ContentPrincipal.cpp
@@ -31,18 +31,16 @@
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/ExtensionPolicyService.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/HashFunctions.h"
 
 using namespace mozilla;
 
-static bool gCodeBasePrincipalSupport = false;
-
 static bool URIIsImmutable(nsIURI* aURI)
 {
   nsCOMPtr<nsIMutable> mutableObj(do_QueryInterface(aURI));
   bool isMutable;
   return
     mutableObj &&
     NS_SUCCEEDED(mutableObj->GetMutable(&isMutable)) &&
     !isMutable;
@@ -58,25 +56,16 @@ NS_IMPL_CLASSINFO(ContentPrincipal, null
                   NS_PRINCIPAL_CID)
 NS_IMPL_QUERY_INTERFACE_CI(ContentPrincipal,
                            nsIPrincipal,
                            nsISerializable)
 NS_IMPL_CI_INTERFACE_GETTER(ContentPrincipal,
                             nsIPrincipal,
                             nsISerializable)
 
-// Called at startup:
-/* static */ void
-ContentPrincipal::InitializeStatics()
-{
-  Preferences::AddBoolVarCache(&gCodeBasePrincipalSupport,
-                               "signed.applets.codebase_principal_support",
-                               false);
-}
-
 ContentPrincipal::ContentPrincipal()
   : BasePrincipal(eCodebasePrincipal)
   , mCodebaseImmutable(false)
   , mDomainImmutable(false)
 {
 }
 
 ContentPrincipal::~ContentPrincipal()

--- a/caps/ContentPrincipal.h
+++ b/caps/ContentPrincipal.h
@@ -35,21 +35,16 @@ public:
 
   // Init() must be called before the principal is in a usable state.
   nsresult Init(nsIURI* aCodebase,
                 const mozilla::OriginAttributes& aOriginAttributes,
                 const nsACString& aOriginNoSuffix);
 
   virtual nsresult GetScriptLocation(nsACString& aStr) override;
 
-  /**
-   * Called at startup to setup static data, e.g. about:config pref-observers.
-   */
-  static void InitializeStatics();
-
   static nsresult
   GenerateOriginNoSuffixFromURI(nsIURI* aURI, nsACString& aOrigin);
 
   mozilla::extensions::WebExtensionPolicy* AddonPolicy();
 
   nsCOMPtr<nsIURI> mDomain;
   nsCOMPtr<nsIURI> mCodebase;
   // If mCodebaseImmutable is true, mCodebase is non-null and immutable

--- a/dom/ipc/ContentPrefs.cpp
+++ b/dom/ipc/ContentPrefs.cpp
@@ -302,17 +302,16 @@ const char* mozilla::dom::ContentPrefs::
   "security.mixed_content.hsts_priming_cache_timeout",
   "security.mixed_content.send_hsts_priming",
   "security.mixed_content.use_hsts",
   "security.sandbox.content.level",
   "security.sandbox.content.tempDirSuffix",
   "security.sandbox.logging.enabled",
   "security.sandbox.mac.track.violations",
   "security.sandbox.windows.log.stackTraceDepth",
-  "signed.applets.codebase_principal_support",
   "svg.disabled",
   "svg.display-lists.hit-testing.enabled",
   "svg.display-lists.painting.enabled",
   "svg.new-getBBox.enabled",
   "svg.paint-order.enabled",
   "svg.path-caching.enabled",
   "svg.transform-box.enabled",
   "toolkit.asyncshutdown.crash_timeout",

--- a/js/src/tests/user.js
+++ b/js/src/tests/user.js
@@ -7,17 +7,16 @@ user_pref("security.fileuri.strict_origi
 user_pref("dom.allow_scripts_to_close_windows", true);
 user_pref("dom.disable_open_during_load", false);
 user_pref("dom.max_script_run_time", 0);
 user_pref("hangmonitor.timeout", 0);
 user_pref("dom.max_chrome_script_run_time", 0);
 user_pref("javascript.allow.mailnews", true);
 user_pref("javascript.options.showInConsole", true);
 user_pref("layout.css.report_errors", true);
-user_pref("signed.applets.codebase_principal_support", true);
 user_pref("browser.warnOnQuit", false);
 user_pref("browser.cache.check_doc_frequency", 1);
 user_pref("extensions.checkCompatibility", false);
 user_pref("extensions.checkUpdateSecurity", false);
 user_pref("browser.EULA.override", true);
 user_pref("javascript.options.strict", false);
 user_pref("javascript.options.werror", false);
 user_pref("toolkit.startup.max_resumed_crashes", -1);

--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -31,17 +31,16 @@
 #include "nsFrame.h"
 #include "nsGlobalWindow.h"
 #include "nsGkAtoms.h"
 #include "nsImageFrame.h"
 #include "nsLayoutStylesheetCache.h"
 #ifdef MOZ_OLD_STYLE
 #include "mozilla/RuleProcessorCache.h"
 #endif
-#include "ContentPrincipal.h"
 #include "nsRange.h"
 #include "nsRegion.h"
 #include "nsRepeatService.h"
 #include "nsFloatManager.h"
 #include "nsSprocketLayout.h"
 #include "nsStackLayout.h"
 #ifdef MOZ_OLD_STYLE
 #include "nsStyleSet.h"
@@ -259,17 +258,16 @@ nsLayoutStatics::Initialize()
   CubebUtils::InitLibrary();
 
   nsContentSink::InitializeStatics();
   nsHtml5Module::InitializeStatics();
   mozilla::dom::FallbackEncoding::Initialize();
   nsLayoutUtils::Initialize();
   PointerEventHandler::InitializeStatics();
   TouchManager::InitializeStatics();
-  ContentPrincipal::InitializeStatics();
 
   nsCORSListenerProxy::Startup();
 
   nsWindowMemoryReporter::Init();
 
   SVGElementFactory::Init();
   nsSVGUtils::Init();
 

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2579,17 +2579,16 @@ pref("font.name-list.sans-serif.x-math",
 pref("font.name-list.monospace.x-math", "monospace");
 
 // Some CJK fonts have bad underline offset, their CJK character glyphs are overlapped (or adjoined)  to its underline.
 // These fonts are ignored the underline offset, instead of it, the underline is lowered to bottom of its em descent.
 pref("font.blacklist.underline_offset", "FangSong,Gulim,GulimChe,MingLiU,MingLiU-ExtB,MingLiU_HKSCS,MingLiU-HKSCS-ExtB,MS Gothic,MS Mincho,MS PGothic,MS PMincho,MS UI Gothic,PMingLiU,PMingLiU-ExtB,SimHei,SimSun,SimSun-ExtB,Hei,Kai,Apple LiGothic,Apple LiSung,Osaka");
 
 pref("security.directory",              "");
 
-pref("signed.applets.codebase_principal_support", false);
 // security-sensitive dialogs should delay button enabling. In milliseconds.
 pref("security.dialog_enable_delay", 1000);
 pref("security.notification_enable_delay", 500);
 
 pref("security.csp.enable", true);
 pref("security.csp.experimentalEnabled", false);
 pref("security.csp.enableStrictDynamic", true);
 #ifdef NIGHTLY_BUILD

--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -17,17 +17,16 @@ user_pref("dom.forms.datetime", true); /
 user_pref("dom.forms.datetime.others", true); // on for testing
 user_pref("dom.max_script_run_time", 0); // no slow script dialogs
 user_pref("hangmonitor.timeout", 0); // no hang monitor
 user_pref("dom.max_chrome_script_run_time", 0);
 user_pref("dom.ipc.reportProcessHangs", false); // process hang monitor
 user_pref("dom.popup_maximum", -1);
 user_pref("dom.send_after_paint_to_content", true);
 user_pref("dom.successive_dialog_time_limit", 0);
-user_pref("signed.applets.codebase_principal_support", true);
 user_pref("browser.shell.checkDefaultBrowser", false);
 user_pref("shell.checkDefaultClient", false);
 user_pref("browser.warnOnQuit", false);
 user_pref("accessibility.typeaheadfind.autostart", false);
 user_pref("findbar.highlightAll", false);
 user_pref("findbar.modalHighlight", false);
 user_pref("javascript.options.showInConsole", true);
 user_pref("devtools.browsertoolbox.panel", "jsdebugger");