[vm] Change TypedData_getUint64 native method to silently cast values

runtime/vm/object.h

 // 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.
 
 #ifndef RUNTIME_VM_OBJECT_H_
 #define RUNTIME_VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 6404 matching lines @@
 
  private:
   OBJECT_IMPLEMENTATION(Number, Instance);
 
   friend class Class;
 };
 
 class Integer : public Number {
  public:
   static RawInteger* New(const String& str, Heap::Space space = Heap::kNew);
+
+  // Creates a new Integer by given uint64_t value.
+  // In the --limit-ints-to-64-bits mode silently casts value to int64_t
+  // (with wrap-around if it is greater than kMaxInt64).
   static RawInteger* NewFromUint64(uint64_t value,
                                    Heap::Space space = Heap::kNew);
 
   // Returns a canonical Integer object allocated in the old gen space.
   // Returns null if integer is out of range (in --limit-ints-to-64-bits mode).
   static RawInteger* NewCanonical(const String& str);
 
   static RawInteger* New(int64_t value, Heap::Space space = Heap::kNew);
 
+  // Returns true iff the given uint64_t value is representable as Dart integer.
+  static bool IsValidUint64(uint64_t value);
+
   virtual bool OperatorEquals(const Instance& other) const {
     return Equals(other);
   }
   virtual bool CanonicalizeEquals(const Instance& other) const {
     return Equals(other);
   }
   virtual uword ComputeCanonicalTableHash() const {
     UNREACHABLE();
     return 0;
   }
@@ skipping 2541 matching lines @@
 
 inline void TypeArguments::SetHash(intptr_t value) const {
   // This is only safe because we create a new Smi, which does not cause
   // heap allocation.
   StoreSmi(&raw_ptr()->hash_, Smi::New(value));
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_OBJECT_H_