Replace our home-grown BitCast with bit_cast from Chrome/Google3.

src/compiler/operator.h

Index: src/compiler/operator.h
diff --git a/src/compiler/operator.h b/src/compiler/operator.h
index bb318d846df189d4e9fc1aeff968e6ac9f8f9472..471bb1e116487c87e464a66c00c17703dca4f750 100644
--- a/src/compiler/operator.h
+++ b/src/compiler/operator.h
@@ -171,10 +171,10 @@ struct StaticParameterTraits<double> {
     return os << val;
   }
   static int HashCode(double a) {
-    return static_cast<int>(BitCast<int64_t>(a));
+    return static_cast<int>(bit_cast<int64_t>(a));
   }
   static bool Equals(double a, double b) {
-    return BitCast<int64_t>(a) == BitCast<int64_t>(b);
+    return bit_cast<int64_t>(a) == bit_cast<int64_t>(b);
   }
 };