A64: fix cctest/test-code-stubs-a64/ConvertDToI.

test/cctest/test-code-stubs-a64.cc

Index: test/cctest/test-code-stubs-a64.cc
diff --git a/test/cctest/test-code-stubs-a64.cc b/test/cctest/test-code-stubs-a64.cc
index 5f82d05c9f5c8394335890730719c84af3aab8a8..9416b19dda06e82dde0d6ef4816f5489e5c87e2d 100644
--- a/test/cctest/test-code-stubs-a64.cc
+++ b/test/cctest/test-code-stubs-a64.cc
@@ -46,8 +46,8 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
                                               Register destination_reg,
                                               bool inline_fastpath) {
   // Allocate an executable page of memory.
-  size_t actual_size;
-  byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
+  size_t actual_size = 2 * Assembler::kMinimalBufferSize;
+  byte* buffer = static_cast<byte*>(OS::Allocate(actual_size,
                                                  &actual_size,
                                                  true));
   CHECK(buffer);