Make in process stack dumping optional.

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index 82e854e7f21b3b7b0f4e77599919be6b402ce8f9..252135b5dd160992f900bd35b616db262702eb83 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -303,7 +303,8 @@ class ShellOptions {
         snapshot_blob(NULL),
         trace_enabled(false),
         trace_config(NULL),
-        lcov_file(NULL) {}
+        lcov_file(NULL),
+        disable_in_process_stack_traces(false) {}
 
   ~ShellOptions() {
     delete[] isolate_sources;
@@ -334,6 +335,7 @@ class ShellOptions {
   bool trace_enabled;
   const char* trace_config;
   const char* lcov_file;
+  bool disable_in_process_stack_traces;
 };
 
 class Shell : public i::AllStatic {