A64: Add support for floating-point registers in PushSafepointRegistersScope.

src/a64/assembler-a64.h

Index: src/a64/assembler-a64.h
diff --git a/src/a64/assembler-a64.h b/src/a64/assembler-a64.h
index e67a75f32680797daff3cd024618b423b1d86d87..7c2bfb859424fbeeaa1a39de8b177c77f4bb554f 100644
--- a/src/a64/assembler-a64.h
+++ b/src/a64/assembler-a64.h
@@ -256,6 +256,8 @@ class FPRegister : public CPURegister {
   static const int kMaxNumAllocatableRegisters =
       kNumberOfFPRegisters - kNumReservedRegisters;
   static int NumAllocatableRegisters() { return kMaxNumAllocatableRegisters; }
+  static const RegList kAllocatableFPRegisters =
+      (1 << kMaxNumAllocatableRegisters) - 1;
 
   static FPRegister FromAllocationIndex(int index) {
     ASSERT((index >= 0) && (index < NumAllocatableRegisters()));