Handle Bigint.toCString when remainder equals 0.

runtime/vm/bigint_operations_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 "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/unit_test.h"
 
@@ skipping 482 matching lines @@
     EXPECT_EQ(0x123, smi.Value());
   }
 
   {
     const Bigint& bigint = Bigint::Handle(
         BigintOperations::NewFromCString("0x000000123"));
     const char* str =
         BigintOperations::ToDecimalCString(bigint, &ZoneAllocator);
     EXPECT_STREQ("291", str);
   }
+
+  {
+    const Bigint& bigint = Bigint::Handle(
+        BigintOperations::NewFromCString("100000000000000000000000000000000"));
+    const char* str =
+        BigintOperations::ToDecimalCString(bigint, &ZoneAllocator);
+    EXPECT_STREQ("100000000000000000000000000000000", str);
+  }
 }
 
 
 static void TestBigintCompare(const char* a, const char* b, int compare) {
   const Bigint& bigint_a = Bigint::Handle(BigintOperations::NewFromCString(a));
   const Bigint& bigint_b = Bigint::Handle(BigintOperations::NewFromCString(b));
   int computed_compare = BigintOperations::Compare(bigint_a, bigint_b);
   int inverted_compare = BigintOperations::Compare(bigint_b, bigint_a);
   if (compare == 0) {
     EXPECT(computed_compare == 0);
@@ skipping 1587 matching lines @@
       "123456789012345678901234567890123456789012345678901234567890123456789012"
       "345678901234567890123456789012345678901234567890123456789012345678901234"
       "567890123456789012345678901234567890123456789012345678901234567890123456"
       "789012345678901234567890123456789012345678901234567890123456789012345678"
       "90123456789012345678901234567890",
       "0x1234567890ABCDEF01234567890ABCDEF01234567890ABCDEF01234567890ABCDEF"
       "01234567890ABCDEE");
 }
 
 }  // namespace dart