Ensure that LowerBound and UpperBound return overflow marker when overflow occurs.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index d743e0f5cb3f88eb7aaf9666aec7bd2f58403535..d9dee189d7e1aba0fc5911c8d7642af4081a19e8 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -1720,12 +1720,12 @@ class Range : public ZoneAllocated {
 
   static RangeBoundary ConstantMin(Range* range) {
     if (range == NULL) return RangeBoundary::MinSmi();
-    return range->min().LowerBound();
+    return range->min().LowerBound().Clamp();
   }
 
   static RangeBoundary ConstantMax(Range* range) {
     if (range == NULL) return RangeBoundary::MaxSmi();
-    return range->max().UpperBound();
+    return range->max().UpperBound().Clamp();
   }
 
   // Inclusive.