A64: Handle a few TODOs.

src/a64/utils-a64.h

Index: src/a64/utils-a64.h
diff --git a/src/a64/utils-a64.h b/src/a64/utils-a64.h
index 16c51a9c8b52770b44d09fe738adc1cc34dbd80c..241b8142d578318fcd33ed9dd58f367adf7d670f 100644
--- a/src/a64/utils-a64.h
+++ b/src/a64/utils-a64.h
@@ -41,6 +41,10 @@ R(24) R(25) R(26) R(27) R(28) R(29) R(30) R(31)
 namespace v8 {
 namespace internal {
 
+// These are global assumptions in v8.
+STATIC_ASSERT((static_cast<int32_t>(-1) >> 1) == -1);
+STATIC_ASSERT((static_cast<uint32_t>(-1) >> 1) == 0x7FFFFFFF);
+
 // Floating point representation.
 static inline uint32_t float_to_rawbits(float value) {
   uint32_t bits = 0;