Expose a lower bound of malloc'd memory via heap statistics

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 6e3663273c19a2bdd65baa674bb914831f2c56c3..f1b4cb41771a7a76ba59d7f08b87747e87977f44 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -297,7 +297,7 @@ static Handle<Code> DoGenerateCode(Stub* stub) {
   if (FLAG_profile_hydrogen_code_stub_compilation) {
     timer.Start();
   }
-  Zone zone;
+  Zone zone(isolate->allocator());
   CompilationInfo info(CodeStub::MajorName(stub->MajorKey()), isolate, &zone,
                        stub->GetCodeFlags());
   // Parameter count is number of stack parameters.