Fix the Cygwin build

test/cctest/test-alloc.cc

Index: test/cctest/test-alloc.cc
diff --git a/test/cctest/test-alloc.cc b/test/cctest/test-alloc.cc
index 3d8157d9557d802178051a5ac78c1a7685a30e89..0ccf4b8b664d338aced867d635d1b7ba52318cec 100644
--- a/test/cctest/test-alloc.cc
+++ b/test/cctest/test-alloc.cc
@@ -200,6 +200,7 @@ TEST(CodeRange) {
       size_t allocated = 0;
       void* base = Isolate::Current()->code_range()->
           AllocateRawMemory(requested, &allocated);
+      CHECK(base != NULL);
       blocks.Add(Block(base, static_cast<int>(allocated)));
       current_allocated += static_cast<int>(allocated);
       total_allocated += static_cast<int>(allocated);