Reland "Track field types.".

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index ac6b99dc5fc79315b3d1d410d49c173e35e75928..4250dc7fd6d6112473029a94a7583884a5b7edd0 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -2414,14 +2414,17 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
     Handle<JSFunction> accessor() { return accessor_; }
     Handle<Object> constant() { return constant_; }
     Handle<Map> transition() { return handle(lookup_.GetTransitionTarget()); }
+    Handle<Map> field_map() { return field_map_; }
     HObjectAccess access() { return access_; }
 
    private:
     Type* ToType(Handle<Map> map) { return builder_->ToType(map); }
     Isolate* isolate() { return lookup_.isolate(); }
+    CompilationInfo* top_info() { return builder_->top_info(); }
     CompilationInfo* current_info() { return builder_->current_info(); }
 
     bool LoadResult(Handle<Map> map);
+    void LoadFieldMap(Handle<Map> map);
     bool LookupDescriptor();
     bool LookupInPrototypes();
     bool IsCompatible(PropertyAccessInfo* other);
@@ -2440,6 +2443,7 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
     Handle<JSFunction> accessor_;
     Handle<JSObject> api_holder_;
     Handle<Object> constant_;
+    Handle<Map> field_map_;
     HObjectAccess access_;
   };