ARM64: Use the shifter operand to merge in previous shift instructions.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 155ecc418470f4a1211bc6a5d165b8ca196053ef..0630167698380bcb107fe5e1775f0020cb217c13 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -655,6 +655,10 @@ class HValue : public ZoneObject {
     HYDROGEN_ABSTRACT_INSTRUCTION_LIST(DECLARE_PREDICATE)
   #undef DECLARE_PREDICATE
 
+  bool IsBitwiseBinaryShift() {
+    return IsShl() || IsShr() || IsSar();
+  }
+
   HValue(HType type = HType::Tagged())
       : block_(NULL),
         id_(kNoNumber),