Handle Bigint.toCString when remainder equals 0.

runtime/vm/bigint_operations.cc

Index: runtime/vm/bigint_operations.cc
diff --git a/runtime/vm/bigint_operations.cc b/runtime/vm/bigint_operations.cc
index 71b593bdb4b436199afa7116bd5e84bab1b39802..0de6a96633a7ba039319c2e70855944a12eff303 100644
--- a/runtime/vm/bigint_operations.cc
+++ b/runtime/vm/bigint_operations.cc
@@ -390,8 +390,11 @@ const char* BigintOperations::ToDecimalCString(
   Bigint& remainder = Bigint::Handle();
   while (!rest.IsZero()) {
     DivideRemainder(rest, divisor, &quotient, &remainder);
-    ASSERT(remainder.Length() == 1);
-    intptr_t part = static_cast<intptr_t>(remainder.GetChunkAt(0));
+    ASSERT(remainder.Length() <= 1);
+    intptr_t part = 0;

[kasperl, 2012/03/07 12:47:01]

intptr_t part = (remainder.Length() == 1)
   ? static_cast<intptr_t>(remainder.GetChunkAt(0))
   : 0;

[floitsch, 2012/03/07 12:51:26]

Done.

+    if (remainder.Length() == 1) {
+      part = static_cast<intptr_t>(remainder.GetChunkAt(0));
+    }
     for (int i = 0; i < kPowerOfTen; i++) {
       result[result_pos++] = '0' + (part % 10);
       part /= 10;