Fix lingering switch statement test failures.

pkg/compiler/lib/src/resolution/members.dart

 // Copyright (c) 2012, 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 dart2js.resolution.members;
 
+import 'dart:collection';
+
 import '../common.dart';
 import '../common/names.dart' show Selectors;
 import '../common/resolution.dart' show Resolution;
 import '../compile_time_constants.dart';
 import '../constants/constructors.dart'
     show RedirectingFactoryConstantConstructor;
 import '../constants/expressions.dart';
 import '../constants/values.dart';
 import '../core_types.dart';
 import '../elements/resolution_types.dart';
@@ skipping 4577 matching lines @@
     if (error != null) {
       reporter.reportError(error, infos);
     }
   }
 
   ResolutionResult visitSwitchStatement(SwitchStatement node) {
     node.expression.accept(this);
 
     JumpTarget breakElement = getOrDefineTarget(node);
     Map<String, LabelDefinition> continueLabels = <String, LabelDefinition>{};
+    Set<SwitchCase> switchCasesWithContinues = new HashSet<SwitchCase>();

[sra1, 2017/02/07 01:05:06]

I'd just say new Set and avoid the import.

[Emily Fortuna, 2017/02/07 01:30:56]

Done.

     Link<Node> cases = node.cases.nodes;
     while (!cases.isEmpty) {
       SwitchCase switchCase = cases.head;
       for (Node labelOrCase in switchCase.labelsAndCases) {
         CaseMatch caseMatch = labelOrCase.asCaseMatch();
         if (caseMatch != null) {
           analyzeConstantDeferred(caseMatch.expression);
           continue;
         }
         Label label = labelOrCase;
@@ skipping 47 matching lines @@
     }
 
     addDeferredAction(enclosingElement, () {
       checkCaseExpressions(node);
     });
 
     statementScope.enterSwitch(breakElement, continueLabels);
     node.cases.accept(this);
     statementScope.exitSwitch();
 
+    continueLabels.forEach((String key, LabelDefinition label) {
+      if (label.isContinueTarget) {
+        JumpTarget targetElement = label.target;
+        SwitchCase switchCase = targetElement.statement;
+        switchCasesWithContinues.add(switchCase);
+      }
+    });
+
     // Clean-up unused labels.
     continueLabels.forEach((String key, LabelDefinition label) {
       if (!label.isContinueTarget) {
         JumpTarget targetElement = label.target;
         SwitchCase switchCase = targetElement.statement;
-        registry.undefineTarget(switchCase);
+        if (!switchCasesWithContinues.contains(switchCase)) {
+          registry.undefineTarget(switchCase);
+        }
         registry.undefineLabel(label.label);
       }
     });
     // TODO(15575): We should warn if we can detect a fall through
     // error.
     return const NoneResult();
   }
 
   ResolutionResult visitSwitchCase(SwitchCase node) {
     node.labelsAndCases.accept(this);
@@ skipping 104 matching lines @@
     }
     return const NoneResult();
   }
 }
 
 /// Looks up [name] in [scope] and unwraps the result.
 Element lookupInScope(
     DiagnosticReporter reporter, Node node, Scope scope, String name) {
   return Elements.unwrap(scope.lookup(name), reporter, node);
 }