Run tree shaking in strong-mode baseline tests.

pkg/kernel/testcases/input/unused_methods.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.
+
+class UnusedClass {
+  UnusedClass() {
+    print('Unused');
+  }
+}
+
+abstract class UsedAsBaseClass {
+  void usedInSubclass() {
+    print('Unused');
+  }
+
+  void calledFromB() {
+    this.calledFromSubclass();
+  }
+
+  void calledFromSubclass() {
+    print('Unused');
+  }
+}
+
+class UsedAsInterface {
+  void usedInSubclass() {
+    print('Unused');
+  }
+}
+
+class InstantiatedButMethodsUnused {
+  void usedInSubclass() {
+    print('Unused');
+  }
+}
+
+class ClassA extends UsedAsBaseClass
+    implements UsedAsInterface, InstantiatedButMethodsUnused {
+  void usedInSubclass() {
+    print('A');
+  }
+}
+
+class ClassB extends UsedAsBaseClass
+    implements UsedAsInterface, InstantiatedButMethodsUnused {
+  void usedInSubclass() {
+    print('B');
+    calledFromB();
+  }
+
+  void calledFromSubclass() {}
+}
+
+void baseClassCall(UsedAsBaseClass object) {
+  object.usedInSubclass();
+}
+
+void interfaceCall(UsedAsInterface object) {
+  object.usedInSubclass();
+}
+
+void exactCallA(ClassA object) {
+  object.usedInSubclass();
+}
+
+void exactCallB(ClassB object) {
+  object.usedInSubclass();
+}
+
+unusedTopLevel() {
+  print('Unused');
+}
+
+usedTopLevel() {}
+
+main() {
+  usedTopLevel();
+
+  ClassA a = new ClassA();
+  exactCallA(a);
+  baseClassCall(a);
+  interfaceCall(a);
+
+  ClassB b = new ClassB();
+  exactCallB(b);
+  baseClassCall(b);
+  interfaceCall(b);
+
+  new InstantiatedButMethodsUnused();
+}