Reland - Arm64: Ensure that csp is always aligned to 16 byte values even if jssp is not.

test/cctest/test-code-stubs-arm64.cc

Index: test/cctest/test-code-stubs-arm64.cc
diff --git a/test/cctest/test-code-stubs-arm64.cc b/test/cctest/test-code-stubs-arm64.cc
index 3ad07bf8091cd4ecbda0b5cfbdd7a035ee5bf261..ad8c82d9d10f5a138281964d6425af7b7654576c 100644
--- a/test/cctest/test-code-stubs-arm64.cc
+++ b/test/cctest/test-code-stubs-arm64.cc
@@ -46,7 +46,7 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
                                               Register destination_reg,
                                               bool inline_fastpath) {
   // Allocate an executable page of memory.
-  size_t actual_size = 2 * Assembler::kMinimalBufferSize;
+  size_t actual_size = 4 * Assembler::kMinimalBufferSize;
   byte* buffer = static_cast<byte*>(OS::Allocate(actual_size,
                                                  &actual_size,
                                                  true));