Add debug mode flag to force recompiling debug code for verification.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 1815c9a8d6441176ba61503aa3ba2186ddc30abe..1aaa446a073614efc8ae5bcc7baeeee6acda6c97 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -659,8 +659,9 @@ static bool CompileUnoptimizedCode(CompilationInfo* info) {
 
 MUST_USE_RESULT static MaybeHandle<Code> GetUnoptimizedCodeCommon(
     CompilationInfo* info) {
-  VMState<COMPILER> state(info->isolate());
-  PostponeInterruptsScope postpone(info->isolate());
+  Isolate* isolate = info->isolate();
+  VMState<COMPILER> state(isolate);
+  PostponeInterruptsScope postpone(isolate);
 
   // Parse and update CompilationInfo with the results.
   if (!Parser::ParseStatic(info->parse_info())) return MaybeHandle<Code>();
@@ -679,13 +680,21 @@ MUST_USE_RESULT static MaybeHandle<Code> GetUnoptimizedCodeCommon(
   // Update the shared function info with the scope info. Allocating the
   // ScopeInfo object may cause a GC.
   Handle<ScopeInfo> scope_info =
-      ScopeInfo::Create(info->isolate(), info->zone(), info->scope());
+      ScopeInfo::Create(isolate, info->zone(), info->scope());
   shared->set_scope_info(*scope_info);
 
   // Update the code and feedback vector for the shared function info.
   shared->ReplaceCode(*info->code());
   shared->set_feedback_vector(*info->feedback_vector());
 
+#ifdef DEBUG
+  if (FLAG_always_recompile_debug && !isolate->debug()->is_active() &&
+      !info->closure().is_null() &&
+      info->shared_info()->IsSubjectToDebugging()) {
+    Compiler::CompileDebugCode(info->closure());
+  }
+#endif
+
   return info->code();
 }