[Interpreter] Add option to trace bytecode execution.

src/interpreter/interpreter.h

Index: src/interpreter/interpreter.h
diff --git a/src/interpreter/interpreter.h b/src/interpreter/interpreter.h
index 6075df835f30d6d7f4332d07fcbe0cd8c5ba2d75..290861a75cfbb638719bc75d5cd23b0a1e5897e4 100644
--- a/src/interpreter/interpreter.h
+++ b/src/interpreter/interpreter.h
@@ -115,6 +115,10 @@ class Interpreter {
   void DoStoreLookupSlot(LanguageMode language_mode,
                          compiler::InterpreterAssembler* assembler);
 
+  // Generates code to trace the currently executing bytecode.
+  void DoTraceBytecodeEntry(compiler::InterpreterAssembler* assembler);
+  void DoTraceBytecodeExit(compiler::InterpreterAssembler* assembler);
+
   bool IsInterpreterTableInitialized(Handle<FixedArray> handler_table);
 
   Isolate* isolate_;