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

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index e98fb47a74c4224a54cab9018997f58b74de43da..c17edcba33f18a006c74a351ea073a08a5a472ef 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -4579,7 +4579,7 @@ Handle<Code> MacroAssemblerBuilder(Isolate* isolate,
 
 Handle<Code> CodeStubAssemblerBuilder(Isolate* isolate,
                                       BuiltinDesc const* builtin_desc) {
-  Zone zone;
+  Zone zone(isolate->allocator());
   compiler::CodeStubAssembler assembler(isolate, &zone, builtin_desc->argc,
                                         builtin_desc->flags,
                                         builtin_desc->s_name);