Introduce TypeFeedbackVector, as FixedArray grew constrictive.

src/full-codegen.cc

Index: src/full-codegen.cc
diff --git a/src/full-codegen.cc b/src/full-codegen.cc
index c1642b1980da4d6be40b708a4c65bb6331f7491f..dd7558e8898c5455a8f0326ffee5b51fbf5c1ef9 100644
--- a/src/full-codegen.cc
+++ b/src/full-codegen.cc
@@ -1572,7 +1572,7 @@ void FullCodeGenerator::VisitNativeFunctionLiteral(
       isolate()->factory()->NewSharedFunctionInfo(
           name, literals, FunctionKind::kNormalFunction, code,
           Handle<ScopeInfo>(fun->shared()->scope_info()),
-          Handle<FixedArray>(fun->shared()->feedback_vector()));
+          Handle<TypeFeedbackVector>(fun->shared()->feedback_vector()));
   shared->set_construct_stub(*construct_stub);
 
   // Copy the function data to the shared function info.