[interpreter] Ensure --debug-code works with snapshots.

src/interpreter/interpreter.cc

Index: src/interpreter/interpreter.cc
diff --git a/src/interpreter/interpreter.cc b/src/interpreter/interpreter.cc
index 1ac342d62b1a4186d5f5643e803d27101abb5a91..69411deea0942dc3a4ed6b1bd3c6315460d1e288 100644
--- a/src/interpreter/interpreter.cc
+++ b/src/interpreter/interpreter.cc
@@ -214,9 +214,10 @@ CompilationJob* Interpreter::NewCompilationJob(CompilationInfo* info) {
 
 bool Interpreter::IsDispatchTableInitialized() {
   if (FLAG_trace_ignition || FLAG_trace_ignition_codegen ||
-      FLAG_trace_ignition_dispatches) {
+      FLAG_trace_ignition_dispatches || FLAG_debug_code) {

[rmcilroy, 2016/10/24 13:46:54]

While you are here, there is a bug that GetBytecodeHandler calls
IsDispatchTableInitialized which means any calls to GetBytecodeHandler fail if
any of these flags are set. Could you create a seperate function
(ShouldInitializeDispatchTable) which checks these flags, and have
IsDispatchTableInitialized only check dispatch_table_[0] != nullptr ?

[Michael Starzinger, 2016/10/25 09:46:12]

Done. Actually one of the try-bots ran into this bug. Thanks for the pointers.

     // Regenerate table to add bytecode tracing operations, print the assembly
-    // code generated by TurboFan or instrument handlers with dispatch counters.
+    // code generated by TurboFan, instrument handlers with dispatch counters,
+    // or insert debugging code into the bytecode handlers.
     return false;
   }
   return dispatch_table_[0] != nullptr;