Make it possible to Crankshaft all kinds of stubs.

src/code-stubs.cc

Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index ad418d69cd33e0f061db20ac2347a6cf82e70467..497dde54e7566eac583dcbee7c0019266367c297 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -67,7 +67,7 @@ void CodeStub::RecordCodeGeneration(Code* code, Isolate* isolate) {
 }
 
 
-int CodeStub::GetCodeKind() {
+Code::Kind CodeStub::GetCodeKind() const {
   return Code::STUB;
 }
 
@@ -98,7 +98,7 @@ Handle<Code> PlatformCodeStub::GenerateCode() {
 
   // Copy the generated code into a heap object.
   Code::Flags flags = Code::ComputeFlags(
-      static_cast<Code::Kind>(GetCodeKind()),
+      GetCodeKind(),
       GetICState(),
       GetExtraICState(),
       GetStubType(),
@@ -308,7 +308,7 @@ void ICCompareStub::AddToSpecialCache(Handle<Code> new_object) {
 bool ICCompareStub::FindCodeInSpecialCache(Code** code_out, Isolate* isolate) {
   Factory* factory = isolate->factory();
   Code::Flags flags = Code::ComputeFlags(
-      static_cast<Code::Kind>(GetCodeKind()),
+      GetCodeKind(),
       UNINITIALIZED);
   ASSERT(op_ == Token::EQ || op_ == Token::EQ_STRICT);
   Handle<Object> probe(