Convert all symbols accessor to return read only handles so that it is not necessary to create a ne…

vm/object_test.cc

 // Copyright (c) 2012, 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 "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
@@ skipping 3107 matching lines @@
     value ^= OneByteString::null();
   }
   isolate->heap()->CollectAllGarbage();
   // Weak property key and value should survive due implicit liveness of
   // non-heap objects.
   EXPECT(weak.key() != Object::null());
   EXPECT(weak.value() != Object::null());
   {
     // Weak property and value in new. Key in VM isolate.
     HANDLESCOPE(isolate);
-    String& key = String::Handle();
-    key ^= Symbols::Dot();
     String& value = String::Handle();
     value ^= OneByteString::New("value", Heap::kNew);
     weak ^= WeakProperty::New(Heap::kNew);
-    weak.set_key(key);
+    weak.set_key(Symbols::Dot());
     weak.set_value(value);
+    String& key = String::Handle();
     key ^= OneByteString::null();
     value ^= OneByteString::null();
   }
   isolate->heap()->CollectAllGarbage();
   // Weak property key and value should survive due to cross-generation
   // pointers.
   EXPECT(weak.key() != Object::null());
   EXPECT(weak.value() != Object::null());
   {
     // Weak property and value in old. Key in VM isolate.
     HANDLESCOPE(isolate);
-    String& key = String::Handle();
-    key ^= Symbols::Dot();
     String& value = String::Handle();
     value ^= OneByteString::New("value", Heap::kOld);
     weak ^= WeakProperty::New(Heap::kOld);
-    weak.set_key(key);
+    weak.set_key(Symbols::Dot());
     weak.set_value(value);
+    String& key = String::Handle();
     key ^= OneByteString::null();
     value ^= OneByteString::null();
   }
   isolate->heap()->CollectAllGarbage();
   // Weak property key and value should survive due to cross-generation
   // pointers.
   EXPECT(weak.key() != Object::null());
   EXPECT(weak.value() != Object::null());
 }
 
@@ skipping 320 matching lines @@
   EXPECT_NE(test1.SourceFingerprint(), test3.SourceFingerprint());
   EXPECT_NE(test3.SourceFingerprint(), test4.SourceFingerprint());
   EXPECT_NE(test4.SourceFingerprint(), test5.SourceFingerprint());
   EXPECT_NE(test5.SourceFingerprint(), test6.SourceFingerprint());
   EXPECT_EQ(test6.SourceFingerprint(), test7.SourceFingerprint());
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart