Simplify type argument instantiation cache lookup by introducing an array

runtime/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 "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
@@ skipping 1796 matching lines @@
   other_array.SetAt(1, other_array);
   EXPECT(!array.Equals(other_array));
 
   other_array = Array::New(kArrayLen - 1);
   other_array.SetAt(0, array);
   other_array.SetAt(2, array);
   EXPECT(!array.Equals(other_array));
 
   EXPECT_EQ(0, Object::empty_array().Length());
 
+  EXPECT_EQ(1, Object::zero_array().Length());
+  element = Object::zero_array().At(0);
+  EXPECT(Smi::Cast(element).IsZero());
+
   array.MakeImmutable();
   Object& obj = Object::Handle(array.raw());
   EXPECT(obj.IsArray());
 }
 
 
 TEST_CASE(StringCodePointIterator) {
   const String& str0 = String::Handle(String::New(""));
   String::CodePointIterator it0(str0);
   EXPECT(!it0.Next());
@@ skipping 2187 matching lines @@
   // Simple map.
   //
   // TODO(turnidge): Consider showing something like: {1: 2, 2: 'otter'}
   result = Dart_GetField(lib, NewString("simple_map"));
   EXPECT_VALID(result);
   obj ^= Api::UnwrapHandle(result);
   EXPECT_STREQ("Instance of '_LinkedHashMap'", obj.ToUserCString());
 }
 
 }  // namespace dart