[interpreter] Add ability to preserve bytecode.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 15d48429507a323f41026b8aeefd2d2eacc34b94..145e0b01ae6fddd5c7bd8941044398eb7936ac9d 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -993,7 +993,7 @@ MaybeHandle<Code> GetBaselineCode(Handle<JSFunction> function) {
   // TODO(4280): For now we play it safe and remove the bytecode array when we
   // switch to baseline code. We might consider keeping around the bytecode so
   // that it can be used as the "source of truth" eventually.
-  shared->ClearBytecodeArray();
+  if (!FLAG_ignition_preserve_bytecode) shared->ClearBytecodeArray();
 
   // Update the shared function info with the scope info.
   InstallSharedScopeInfo(&info, shared);
@@ -1434,7 +1434,7 @@ bool Compiler::EnsureDeoptimizationSupport(CompilationInfo* info) {
     // TODO(4280): For now we play it safe and remove the bytecode array when we
     // switch to baseline code. We might consider keeping around the bytecode so
     // that it can be used as the "source of truth" eventually.
-    shared->ClearBytecodeArray();
+    if (!FLAG_ignition_preserve_bytecode) shared->ClearBytecodeArray();
 
     // The scope info might not have been set if a lazily compiled
     // function is inlined before being called for the first time.