Simplify type argument instantiation cache lookup by introducing an array

runtime/vm/snapshot.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/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 741 matching lines @@
   if (object_id == kNullObject) {
     // This is a singleton null object, return it.
     return Object::null();
   }
   if (object_id == kSentinelObject) {
     return Object::sentinel().raw();
   }
   if (object_id == kEmptyArrayObject) {
     return Object::empty_array().raw();
   }
+  if (object_id == kZeroArrayObject) {
+    return Object::zero_array().raw();
+  }
   if (object_id == kDynamicType) {
     return Object::dynamic_type();
   }
   if (object_id == kVoidType) {
     return Object::void_type();
   }
   if (object_id == kTrueValue) {
     return Bool::True().raw();
   }
   if (object_id == kFalseValue) {
@@ skipping 179 matching lines @@
     WriteVMIsolateObject(kSentinelObject);
     return;
   }
 
   // Check if it is a singleton empty array object.
   if (rawobj == Object::empty_array().raw()) {
     WriteVMIsolateObject(kEmptyArrayObject);
     return;
   }
 
+  // Check if it is a singleton zero array object.
+  if (rawobj == Object::zero_array().raw()) {
+    WriteVMIsolateObject(kZeroArrayObject);
+    return;
+  }
+
   // Check if it is a singleton dyanmic Type object.
   if (rawobj == Object::dynamic_type()) {
     WriteVMIsolateObject(kDynamicType);
     return;
   }
 
   // Check if it is a singleton void Type object.
   if (rawobj == Object::void_type()) {
     WriteVMIsolateObject(kVoidType);
     return;
@@ skipping 569 matching lines @@
     NoGCScope no_gc;
     WriteObject(obj.raw());
     UnmarkAll();
   } else {
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart