Fix an issue with duplicate reported analysis errors.

pkg/analyzer_cli/lib/src/error_severity.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/source/error_processor.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisResult;
 import 'package:analyzer_cli/src/error_formatter.dart';
 import 'package:analyzer_cli/src/options.dart';
 
 /// Check various configuration options to get a desired severity for this
 /// [error] (or `null` if it's to be suppressed).
-ProcessedSeverity processError(AnalysisError error,
+ProcessedSeverity determineProcessedSeverity(AnalysisError error,
     CommandLineOptions commandLineOptions, AnalysisOptions analysisOptions) {
   ErrorSeverity severity = computeSeverity(error, commandLineOptions,
       analysisOptions: analysisOptions);
   bool isOverridden = false;
 
   // Skip TODOs categorically (unless escalated to ERROR or HINT.)
   // https://github.com/dart-lang/sdk/issues/26215
   if (error.errorCode.type == ErrorType.TODO &&
       severity == ErrorSeverity.INFO) {
     return null;
@@ skipping 38 matching lines @@
   if (!commandLineOptions.enableTypeChecks &&
       error.errorCode.type == ErrorType.CHECKED_MODE_COMPILE_TIME_ERROR) {
     return ErrorSeverity.INFO;
   } else if (commandLineOptions.hintsAreFatal && error.errorCode is HintCode) {
     return ErrorSeverity.ERROR;
   } else if (commandLineOptions.lintsAreFatal && error.errorCode is LintCode) {
     return ErrorSeverity.ERROR;
   }
   return error.errorCode.errorSeverity;
 }