Fix an issue with duplicate reported analysis errors.

pkg/analyzer_cli/lib/src/build_mode.dart

 // Copyright (c) 2015, 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.
 
 library analyzer_cli.src.build_mode;
 
 import 'dart:core';
 import 'dart:io' as io;
 
 import 'package:analyzer/dart/ast/ast.dart' show CompilationUnit;
@@ skipping 225 matching lines @@
       return _computeMaxSeverity();
     }
   }
 
   ErrorSeverity _computeMaxSeverity() {
     ErrorSeverity maxSeverity = ErrorSeverity.NONE;
     if (!options.buildSuppressExitCode) {
       for (Source source in explicitSources) {
         AnalysisErrorInfo errorInfo = context.getErrors(source);
         for (AnalysisError error in errorInfo.errors) {
-          ProcessedSeverity processedSeverity =
-              processError(error, options, context.analysisOptions);
+          ProcessedSeverity processedSeverity = determineProcessedSeverity(
+              error, options, context.analysisOptions);
           if (processedSeverity != null) {
             maxSeverity = maxSeverity.max(processedSeverity.severity);
           }
         }
       }
     }
     return maxSeverity;
   }
 
   void _createContext() {
@@ skipping 67 matching lines @@
     }
     return uriToFileMap;
   }
 
   /**
    * Print errors for all explicit sources.  If [outputPath] is supplied, output
    * is sent to a new file at that path.
    */
   void _printErrors({String outputPath}) {
     StringBuffer buffer = new StringBuffer();
-    ErrorFormatter formatter = new ErrorFormatter(
-        buffer,
-        options,
-        stats,
-        (AnalysisError error) =>
-            processError(error, options, context.analysisOptions));
+    ErrorFormatter formatter = new HumanErrorFormatter(buffer, options, stats,
+        severityProcessor: (AnalysisError error) => determineProcessedSeverity(
+            error, options, context.analysisOptions));
     for (Source source in explicitSources) {
       AnalysisErrorInfo errorInfo = context.getErrors(source);
       formatter.formatErrors([errorInfo]);
     }
+    formatter.flush();
     if (!options.machineFormat) {
       stats.print(buffer);
     }
     if (outputPath == null) {
       StringSink sink = options.machineFormat ? errorSink : outSink;
       sink.write(buffer);
     } else {
       new io.File(outputPath).writeAsStringSync(buffer.toString());
     }
   }
@@ skipping 86 matching lines @@
    * Build the inverse mapping of [uriToSourceMap].
    */
   static Map<String, Uri> _computePathToUriMap(Map<Uri, File> uriToSourceMap) {
     Map<String, Uri> pathToUriMap = <String, Uri>{};
     uriToSourceMap.forEach((Uri uri, File file) {
       pathToUriMap[file.path] = uri;
     });
     return pathToUriMap;
   }
 }