Fix compiler warning with shift of negative value.

runtime/vm/flow_graph_range_analysis.cc

Index: runtime/vm/flow_graph_range_analysis.cc
diff --git a/runtime/vm/flow_graph_range_analysis.cc b/runtime/vm/flow_graph_range_analysis.cc
index b19b4e63a1778120cd22b7790cfef65e8d6ba73d..d680ea672f6470bb6e867246eacc831986d737ae 100644
--- a/runtime/vm/flow_graph_range_analysis.cc
+++ b/runtime/vm/flow_graph_range_analysis.cc
@@ -2348,7 +2348,7 @@ void Range::BitwiseOp(const Range* left_range,
     *result_min = RangeBoundary::FromConstant(0);
   } else {
     *result_min =
-        RangeBoundary::FromConstant(static_cast<int64_t>(-1) << bitsize);
+        RangeBoundary::FromConstant(-(static_cast<int64_t>(1) << bitsize));
   }
 
   *result_max =