Use PassiveObject were possible.

runtime/vm/bigint_operations.cc

 // Copyright 2012 Google Inc. All Rights Reserved.
 
 #include "vm/bigint_operations.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 
 #include "vm/double_internals.h"
 #include "vm/exceptions.h"
 #include "vm/object_store.h"
@@ skipping 204 matching lines @@
   if ((-1.0 < d) && (d < 1.0)) {
     // Shortcut for small numbers. Also makes the right-shift below
     // well specified.
     Smi& zero = Smi::Handle(Smi::New(0));
     return NewFromSmi(zero, space);
   }
   DoubleInternals internals = DoubleInternals(d);
   if (internals.IsSpecial()) {
     const Array& exception_arguments = Array::Handle(Array::New(1));
     exception_arguments.SetAt(
-        0, Object::Handle(String::New("BigintOperations::NewFromDouble")));
+        0,
+        PassiveObject::Handle(String::New("BigintOperations::NewFromDouble")));
     Exceptions::ThrowByType(Exceptions::kInternalError, exception_arguments);
   }
   uint64_t significand = internals.Significand();
   intptr_t exponent = internals.Exponent();
   intptr_t sign = internals.Sign();
   if (exponent <= 0) {
     significand >>= -exponent;
     exponent = 0;
   } else if (exponent <= 10) {
     // A double significand has at most 53 bits. The following shift will
@@ skipping 1622 matching lines @@
 intptr_t BigintOperations::CountBits(Chunk digit) {
   intptr_t result = 0;
   while (digit != 0) {
     digit >>= 1;
     result++;
   }
   return result;
 }
 
 }  // namespace dart