Follow factory redirections when checking case expressions.

tests/compiler/dart2js/resolver_test.dart

Index: tests/compiler/dart2js/resolver_test.dart
diff --git a/tests/compiler/dart2js/resolver_test.dart b/tests/compiler/dart2js/resolver_test.dart
index 5673e4a02a01cc010beac60786f3282fa793d0a5..5d448c8d92e670a8dc4e2d843b379db40f7611bf 100644
--- a/tests/compiler/dart2js/resolver_test.dart
+++ b/tests/compiler/dart2js/resolver_test.dart
@@ -72,6 +72,7 @@ main() {
   testInitializers();
   testThis();
   testSuperCalls();
+  testSwitch();
   testTypeVariables();
   testToString();
   testIndexedOperator();
@@ -203,6 +204,25 @@ testSuperCalls() {
   Expect.equals(fooA, called);
 }
 
+testSwitch() {
+  MockCompiler compiler = new MockCompiler();
+  compiler.parseScript("class Foo { foo() {"
+      "switch (null) { case '': break; case 2: break; } } }");
+  compiler.resolveStatement("Foo foo;");
+  ClassElement fooElement = compiler.mainApp.find("Foo");
+  FunctionElement funElement = fooElement.lookupLocalMember("foo");
+  compiler.processQueue(compiler.enqueuer.resolution, funElement);
+  Expect.equals(0, compiler.warnings.length);
+  Expect.equals(1, compiler.errors.length);
+  Expect.equals(MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL,
+                compiler.errors[0].message.kind);
+  Expect.equals(2, compiler.infos.length);
+  Expect.equals(MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL_CASE,
+                compiler.infos[0].message.kind);
+  Expect.equals(MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL_CASE,
+                compiler.infos[1].message.kind);
+}
+
 testThis() {
   MockCompiler compiler = new MockCompiler();
   compiler.parseScript("class Foo { foo() { return this; } }");