Fixed assertions on ARM64.

TBR=ulan@chromium.org

Review URL: https://codereview.chromium.org/220763003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20386 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm64/macro-assembler-arm64-inl.h

@@ -1532,7 +1532,7 @@ void MacroAssembler::Claim(const Register& count, uint64_t unit_size) {
 
 
 void MacroAssembler::ClaimBySMI(const Register& count_smi, uint64_t unit_size) {
-  ASSERT(IsPowerOf2(unit_size));
+  ASSERT(unit_size == 0 || IsPowerOf2(unit_size));
   const int shift = CountTrailingZeros(unit_size, kXRegSizeInBits) - kSmiShift;
   const Operand size(count_smi,
                      (shift >= 0) ? (LSL) : (LSR),
@@ -1593,7 +1593,7 @@ void MacroAssembler::Drop(const Register& count, uint64_t unit_size) {
 
 
 void MacroAssembler::DropBySMI(const Register& count_smi, uint64_t unit_size) {
-  ASSERT(IsPowerOf2(unit_size));
+  ASSERT(unit_size == 0 || IsPowerOf2(unit_size));
   const int shift = CountTrailingZeros(unit_size, kXRegSizeInBits) - kSmiShift;
   const Operand size(count_smi,
                      (shift >= 0) ? (LSL) : (LSR),