fix #29585, implement equality for tearoffs

tests/language_strong/tearoff_dynamic_test.dart

Index: tests/language_strong/tearoff_dynamic_test.dart
diff --git a/tests/language_strong/tearoff_dynamic_test.dart b/tests/language_strong/tearoff_dynamic_test.dart
index 9d324d6a6347cccaa9d6e179da32766e4376d23b..e23c22fc493d09ab14e32bdac5903831391748b6 100644
--- a/tests/language_strong/tearoff_dynamic_test.dart
+++ b/tests/language_strong/tearoff_dynamic_test.dart
@@ -5,6 +5,7 @@ import 'package:expect/expect.dart';
 
 class Foo {
   dynamic method(int x) {}
+  dynamic method2(int x) {}
 }
 
 main() {
@@ -15,4 +16,14 @@ main() {
 
   dynamic dynamicMethod2 = (foo as dynamic).method;
   Expect.throws(() => dynamicMethod2(2.5));
+
+  Expect.equals(dynamicMethod1, dynamicMethod1);
+  Expect.equals(dynamicMethod1, dynamicMethod2);
+  Expect.equals(dynamicMethod1, foo.method);
+  Expect.equals(foo.method2, (foo as dynamic).method2);
+
+  Expect.notEquals(dynamicMethod1, new Foo().method);
+  Expect.notEquals(dynamicMethod1, (new Foo() as dynamic).method);
+  Expect.notEquals(dynamicMethod1, foo.method2);
+  Expect.notEquals(dynamicMethod1, (foo as dynamic).method2);
 }