Fix handle sharing bug in implementation of shape changes.

runtime/vm/isolate_reload_test.cc

 // Copyright (c) 2016, 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.
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
@@ skipping 2758 matching lines @@
   EXPECT_VALID(lib);
 
   const char* kReloadScript =
       "class Foo<A> {\n"
       "  var a;\n"
       "}\n";
   lib = TestCase::ReloadTestScript(kReloadScript);
   EXPECT_VALID(lib);
 }
 
+
+// Regression for handle sharing bug: Change the shape of two classes and see
+// that their instances don't change class.
+TEST_CASE(IsolateReload_ChangeInstanceFormat8) {
+  const char* kScript =
+      "class A{\n"
+      "  var x;\n"
+      "}\n"
+      "class B {\n"
+      "  var x, y, z, w;\n"
+      "}\n"
+      "var a, b;\n"
+      "main() {\n"
+      "  a = new A();\n"
+      "  b = new B();\n"
+      "  return '$a $b';\n"
+      "}\n";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("Instance of 'A' Instance of 'B'", SimpleInvokeStr(lib, "main"));
+
+  const char* kReloadScript =
+      "class A{\n"
+      "  var x, y;\n"
+      "}\n"
+      "class B {\n"
+      "  var x, y, z, w, v;\n"
+      "}\n"
+      "var a, b;\n"
+      "main() {\n"
+      "  return '$a $b';\n"
+      "}\n";
+
+  lib = TestCase::ReloadTestScript(kReloadScript);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("Instance of 'A' Instance of 'B'", SimpleInvokeStr(lib, "main"));
+}
+
+
 static bool NothingModifiedCallback(const char* url, int64_t since) {
   return false;
 }
 
 
 TEST_CASE(IsolateReload_NoLibsModified) {
   const char* kImportScript =
       "importedFunc() => 'fancy';";
   TestCase::AddTestLib("test:lib1", kImportScript);
 
@@ skipping 191 matching lines @@
   EXPECT_VALID(lib);
   Dart_SetFileModifiedCallback(NULL);
 
   // Modification of an exported library propagates.
   EXPECT_STREQ("bossy pants", SimpleInvokeStr(lib, "main"));
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart