Canonicalize all integer constants taht we create by parsing a string.

runtime/vm/snapshot_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 "include/dart_debugger_api.h"
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_message.h"
@@ skipping 357 matching lines @@
 
 
 TEST_CASE(SerializeBigint) {
   StackZone zone(Isolate::Current());
 
   // Write snapshot with object content.
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator);
   const char* cstr = "0x270FFFFFFFFFFFFFD8F0";
   const String& str = String::Handle(String::New(cstr));
-  const Bigint& bigint = Bigint::Handle(Bigint::New(str));
+  const Bigint& bigint = Bigint::Handle(Bigint::NewCanonical(str));
   writer.WriteMessage(bigint);
   intptr_t buffer_len = writer.BytesWritten();
 
   // Read object back from the snapshot.
   SnapshotReader reader(buffer, buffer_len,
                         Snapshot::kMessage, Isolate::Current());
   Bigint& obj = Bigint::Handle();
   obj ^= reader.ReadObject();
 
   EXPECT_STREQ(BigintOperations::ToHexCString(bigint, &allocator),
@@ skipping 1758 matching lines @@
   EXPECT(Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("Exception: nulltruefalse123456æøå3.14[]100123456789\n",
                    Dart_GetError(result));
 
   Dart_ExitScope();
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart