Bug 1697467 - Fix a typo, I don't know how to boolean.

MANUAL PUSH: Orange in a CLOSED TREE.

layout/style/GeckoBindings.cpp

@@ -715,7 +715,7 @@ static bool ShouldUseStandinsForNativeColorForNonNativeTheme(
 
     case ColorID::Field:
     case ColorID::Fieldtext:
-      return PreferenceSheet::PrefsFor(aDoc).mUseAccessibilityTheme;
+      return !PreferenceSheet::PrefsFor(aDoc).mUseAccessibilityTheme;
 
     default:
       break;