Fix right shifting of a Mint value by an amount larger than 63.

runtime/lib/integers.cc

Index: runtime/lib/integers.cc
diff --git a/runtime/lib/integers.cc b/runtime/lib/integers.cc
index b1ca62c3e311877ca86ac568531c416d42b56f18..e8d655ca416b741a98b559dfacaf451788bea44b 100644
--- a/runtime/lib/integers.cc
+++ b/runtime/lib/integers.cc
@@ -275,7 +275,9 @@ static RawInteger* ShiftOperationHelper(Token::Kind kind,
         case Token::kSHL:
           return Integer::New(mint_value << shift_count, Heap::kNew, silent);
         case Token::kSHR:
-          return Integer::New(mint_value >> -shift_count, Heap::kNew, silent);
+          shift_count =
+              (-shift_count > Mint::kBits) ? Mint::kBits : -shift_count;
+          return Integer::New(mint_value >> shift_count, Heap::kNew, silent);
         default:
           UNIMPLEMENTED();
       }