fixup! Bug 41918: Option to reuse last window size when letterboxing is enabled.

Fixes typo in RFHelper.sys.mjs (Service -> Services).

toolkit/components/resistfingerprinting/RFPHelper.sys.mjs

@@ -223,7 +223,7 @@ class _RFPHelper {
   _handlePrefChanged(data) {
     switch (data) {
       case kPrefResistFingerprinting:
-        Service.prefs.clearUserPref(kPrefLetterboxingDidForceSize);
+        Services.prefs.clearUserPref(kPrefLetterboxingDidForceSize);
         this._handleResistFingerprintingChanged();
         break;
       case kPrefSpoofEnglish:
@@ -231,7 +231,7 @@ class _RFPHelper {
         this._handleSpoofEnglishChanged();
         break;
       case kPrefLetterboxing:
-        Service.prefs.clearUserPref(kPrefLetterboxingDidForceSize);
+        Services.prefs.clearUserPref(kPrefLetterboxingDidForceSize);
       case kPrefLetterboxingVcenter:
       case kPrefLetterboxingGradient:
         this._handleLetterboxingPrefChanged();