Massage the CodeStub class hierarchy a bit.

src/compiler.h

Index: src/compiler.h
diff --git a/src/compiler.h b/src/compiler.h
index 2f6beba0297808824bced1e5fd484f833f9b8e31..381eb2a7595c6ce4947417f16bc1fda3bf2e1b92 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -121,7 +121,7 @@ class CompilationInfo {
   Handle<SharedFunctionInfo> shared_info() const { return shared_info_; }
   Handle<Script> script() const { return script_; }
   void set_script(Handle<Script> script) { script_ = script; }
-  HydrogenCodeStub* code_stub() const {return code_stub_; }
+  CodeStub* code_stub() const { return code_stub_; }
   v8::Extension* extension() const { return extension_; }
   ScriptData** cached_data() const { return cached_data_; }
   ScriptCompiler::CompileOptions compile_options() const {
@@ -475,7 +475,7 @@ class CompilationInfo {
   // The script scope provided as a convenience.
   Scope* script_scope_;
   // For compiled stubs, the stub object
-  HydrogenCodeStub* code_stub_;
+  CodeStub* code_stub_;
   // The compiled code.
   Handle<Code> code_;