Check in codegen test expectations.

test/codegen/expect/language/string_interpolation7_test.js

Index: test/codegen/expect/language/string_interpolation7_test.js
diff --git a/test/codegen/expect/language/string_interpolation7_test.js b/test/codegen/expect/language/string_interpolation7_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..688d77dc7f3052e2e7ac0ede2736a9962c0e0af3
--- /dev/null
+++ b/test/codegen/expect/language/string_interpolation7_test.js
@@ -0,0 +1,40 @@
+dart_library.library('language/string_interpolation7_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__string_interpolation7_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const string_interpolation7_test = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  string_interpolation7_test.A = class A extends core.Object {
+    new() {
+    }
+    toString() {
+      return "A";
+    }
+  };
+  dart.setSignature(string_interpolation7_test.A, {
+    constructors: () => ({new: dart.definiteFunctionType(string_interpolation7_test.A, [])})
+  });
+  string_interpolation7_test.StringInterpolation7Test = class StringInterpolation7Test extends core.Object {
+    static testMain() {
+      let a = new string_interpolation7_test.A();
+      expect$.Expect.equals("A + A", dart.str`${a} + ${a}`);
+      a = null;
+      expect$.Expect.equals("null", dart.str`${a}`);
+    }
+  };
+  dart.setSignature(string_interpolation7_test.StringInterpolation7Test, {
+    statics: () => ({testMain: dart.definiteFunctionType(dart.dynamic, [])}),
+    names: ['testMain']
+  });
+  string_interpolation7_test.main = function() {
+    string_interpolation7_test.StringInterpolation7Test.testMain();
+  };
+  dart.fn(string_interpolation7_test.main, VoidTodynamic());
+  // Exports:
+  exports.string_interpolation7_test = string_interpolation7_test;
+});