harmony-scoping: Implement StoreIC handler for stores to global contexts.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index 810a149936fc6226df794e8f2f3f42b7e0880be0..82d48a24f85ad03658c047397b5329751b3c9565 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -1396,6 +1396,13 @@ MaybeHandle<Object> StoreIC::Store(Handle<Object> object, Handle<Name> name,
       if (lookup_result.mode == CONST) {
         return TypeError("harmony_const_assign", object, name);
       }
+
+      if (FLAG_use_ic &&
+          StoreGlobalContextFieldStub::Accepted(&lookup_result)) {
+        StoreGlobalContextFieldStub stub(isolate(), &lookup_result);
+        PatchCache(name, stub.GetCode());
+      }
+
       global_context->set(lookup_result.slot_index, *value);
       return value;
     }