Add an interface for retrieving the value of unsigned 64-bit integers.

runtime/vm/bigint_operations.h

Index: runtime/vm/bigint_operations.h
diff --git a/runtime/vm/bigint_operations.h b/runtime/vm/bigint_operations.h
index ce2916c02d387f73fb871e92a838c8ea50e764ee..70d12e3935817d9d7cc07af82f71700f401a0d23 100644
--- a/runtime/vm/bigint_operations.h
+++ b/runtime/vm/bigint_operations.h
@@ -20,7 +20,7 @@ class BigintOperations : public AllStatic {
  public:
   static RawBigint* NewFromSmi(const Smi& smi, Heap::Space space = Heap::kNew);
   static RawBigint* NewFromInt64(int64_t value, Heap::Space space = Heap::kNew);
-  static RawBigint* NewFromUInt64(uint64_t value,
+  static RawBigint* NewFromUint64(uint64_t value,
                                   Heap::Space space = Heap::kNew);
   // The given string must be a valid integer representation. It may be
   // prefixed by a minus and/or "0x".
@@ -57,9 +57,9 @@ class BigintOperations : public AllStatic {
   static bool FitsIntoInt64(const Bigint& bigint);
   static int64_t ToInt64(const Bigint& bigint);
 
-  static bool FitsIntoUInt64(const Bigint& bigint);
-  static uint64_t ToUInt64(const Bigint& bigint);
-  static uint64_t AbsToUInt64(const Bigint& bigint);
+  static bool FitsIntoUint64(const Bigint& bigint);
+  static uint64_t ToUint64(const Bigint& bigint);
+  static uint64_t AbsToUint64(const Bigint& bigint);
 
   static RawDouble* ToDouble(const Bigint& bigint);