Hydrogen code stubs for vector-based ICs.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index cfc2a81feee0f1d6119e3da25f3551bbe659321a..9523159c47a28dd33ffe04a755ebf0896cf84757 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -665,8 +665,6 @@ void IC::ConfigureVectorState(IC::State new_state) {
       nexus->ConfigureGeneric();
     } else if (new_state == PREMONOMORPHIC) {
       nexus->ConfigurePremonomorphic();
-    } else if (new_state == MEGAMORPHIC) {
-      nexus->ConfigureMegamorphic();
     } else {
       UNREACHABLE();
     }
@@ -971,7 +969,8 @@ void IC::PatchCache(Handle<Name> name, Handle<Code> code) {
         CopyICToMegamorphicCache(name);
       }
       if (UseVector()) {
-        ConfigureVectorState(MEGAMORPHIC);
+        ConfigureVectorState(kind() == Code::KEYED_LOAD_IC ? GENERIC
+                                                           : MEGAMORPHIC);
       } else {
         set_target(*megamorphic_stub());
       }