ARM64: Change some incorect uses of ptrdiff_t to int64_t.

src/arm64/lithium-codegen-arm64.cc

Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index 904eecd2e10a0b2672249241dabf62b2d28ddc9a..5c6653515a0ceb5726f48b137e3edbe897b96ab6 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -1248,7 +1248,7 @@ Operand LCodeGen::ToOperand32(LOperand* op) {
 }
 
 
-static ptrdiff_t ArgumentsOffsetWithoutFrame(ptrdiff_t index) {
+static int64_t ArgumentsOffsetWithoutFrame(int index) {
   DCHECK(index < 0);
   return -(index + 1) * kPointerSize;
 }