[interpreter] Be explicit when to test BytecodeGraphBuilder.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index eeb8d068a06031e41c0b194499ec12d26a5e473f..22e8b487eecbbae2cde9ae23277d6103835b64b4 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -839,7 +839,8 @@ MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
                    : new HCompilationJob(info.get()));
 
   // TruboFan can optimize directly from existing bytecode.
-  if (use_turbofan && info->shared_info()->HasBytecodeArray()) {
+  if (FLAG_turbo_from_bytecode && use_turbofan &&
+      info->shared_info()->HasBytecodeArray()) {
     info->MarkAsOptimizeFromBytecode();
   }