anchor.diff:  const _argProfileFor = 'profile';
   const _argLegacyStyle = 'use_legacy_style_encapsulation';
   const _argFastBoot = 'fast_boot';
  +const _argLegacyWhitespace = 'use_legacy_preserve_whitespace';
   
   /// Compiler-wide configuration (flags) to allow opting in/out.
   ///
  
positive.code:       log('Invalid value for "$_argFastBoot": $useFastBoot');
        useFastBoot = null;
      }
      return new CompilerFlags(
        genDebugInfo: debugMode ?? defaultTo.genDebugInfo,
        profileFor: _toProfile(profileFor, log) ?? defaultTo.profileFor,
        useLegacyStyleEncapsulation:
            useLegacyStyle ?? defaultTo.useLegacyStyleEncapsulation,
        useFastBoot: useFastBoot ?? defaultTo.useFastBoot,
      );
    }
  }
  
negative.code:         _argProfileFor,
          _argLegacyStyle,
          _argFastBoot,
          _argLegacyWhitespace
        ].toSet();
        final unknownArgs = options.keys.toSet().difference(knownArgs);
        if (unknownArgs.isNotEmpty) {
  