fix #26122, classify strong mode errors correctly

pkg/analyzer_cli/lib/src/analyzer_impl.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.analyzer_impl;
 
 import 'dart:collection';
 import 'dart:io';
 
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 241 matching lines @@
   }
 
   /// Compute the severity of the error; however:
   ///   * if [options.enableTypeChecks] is false, then de-escalate checked-mode
   ///   compile time errors to a severity of [ErrorSeverity.INFO].
   ///   * if [options.hintsAreFatal] is true, escalate hints to errors.
   ///   * if [options.lintsAreFatal] is true, escalate lints to errors.
   static ErrorSeverity computeSeverity(
       AnalysisError error, CommandLineOptions options,
       [AnalysisContext context]) {
-    bool isStrongMode = false;
     if (context != null) {
       ErrorProcessor processor = ErrorProcessor.getProcessor(context, error);
       // If there is a processor for this error, defer to it.
       if (processor != null) {
         return processor.severity;
       }
-      isStrongMode = context.analysisOptions.strongMode;
     }
 
     if (!options.enableTypeChecks &&
         error.errorCode.type == ErrorType.CHECKED_MODE_COMPILE_TIME_ERROR) {
       return ErrorSeverity.INFO;
     } else if (options.hintsAreFatal && error.errorCode is HintCode) {
       return ErrorSeverity.ERROR;
     } else if (options.lintsAreFatal && error.errorCode is LintCode) {
       return ErrorSeverity.ERROR;
-    } else if (isStrongMode &&
-        error is StaticWarningCode &&
-        (error as StaticWarningCode).isStrongModeError) {
-      return ErrorSeverity.ERROR;
     }
     return error.errorCode.errorSeverity;
   }
 
   /// Return the corresponding package directory or `null` if none is found.
   static JavaFile getPackageDirectoryFor(JavaFile sourceFile) {
     // We are going to ask parent file, so get absolute path.
     sourceFile = sourceFile.getAbsoluteFile();
     // Look in the containing directories.
     JavaFile dir = sourceFile.getParentFile();
@@ skipping 70 matching lines @@
   }
 
   @override
   void logInformation(String message, [CaughtException exception]) {
     outSink.writeln(message);
     if (exception != null) {
       outSink.writeln(exception);
     }
   }
 }