Get code flags from compilation info.

Removed useless (and in the future incorrect) DCHECKs on the way.

Review URL: https://codereview.chromium.org/921443004

Cr-Commit-Position: refs/heads/master@{#26655}

src/compiler/code-generator.cc

@@ -125,13 +125,8 @@ Handle<Code> CodeGenerator::GenerateCode() {
 
   safepoints()->Emit(masm(), frame()->GetSpillSlotCount());
 
-  // TODO(titzer): what are the right code flags here?
-  Code::Kind kind = Code::STUB;
-  if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
-    kind = Code::OPTIMIZED_FUNCTION;
-  }
   Handle<Code> result = v8::internal::CodeGenerator::MakeCodeEpilogue(
-      masm(), Code::ComputeFlags(kind), info);
+      masm(), info->flags(), info);
   result->set_is_turbofanned(true);
   result->set_stack_slots(frame()->GetSpillSlotCount());
   result->set_safepoint_table_offset(safepoints()->GetCodeOffset());

src/objects-inl.h

@@ -4869,14 +4869,12 @@ inline void Code::set_is_crankshafted(bool value) {
 
 
 inline bool Code::is_turbofanned() {
-  DCHECK(kind() == OPTIMIZED_FUNCTION || kind() == STUB);
   return IsTurbofannedField::decode(
       READ_UINT32_FIELD(this, kKindSpecificFlags1Offset));
 }
 
 
 inline void Code::set_is_turbofanned(bool value) {
-  DCHECK(kind() == OPTIMIZED_FUNCTION || kind() == STUB);
   int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
   int updated = IsTurbofannedField::update(previous, value);
   WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);