[ic] Load 'integer indexed exotic' (oob) as simple nonexistent fields

This is just a very minor cleanup avoiding unnecessary slow stub usage.

BUG=v8:5561

Change-Id: Ib145606520b5b7019f1e55d3aec7caa956c7e090
Reviewed-on: https://chromium-review.googlesource.com/457337Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43989}

src/counters.h

@@ -786,6 +786,7 @@ class RuntimeCallTimer final {
   V(LoadIC_LoadFieldFromPrototypeDH)             \
   V(LoadIC_LoadField)                            \
   V(LoadIC_LoadGlobalFromPrototypeDH)            \
+  V(LoadIC_LoadIntegerIndexedExoticDH)           \
   V(LoadIC_LoadInterceptorDH)                    \
   V(LoadIC_LoadNonMaskingInterceptorDH)          \
   V(LoadIC_LoadInterceptorFromPrototypeDH)       \

src/ic/ic.cc

@@ -1376,8 +1376,8 @@ Handle<Object> LoadIC::GetMapIndependentHandler(LookupIterator* lookup) {
       return LoadFromPrototype(map, holder, lookup->name(), smi_handler);
     }
     case LookupIterator::INTEGER_INDEXED_EXOTIC:
-      TRACE_HANDLER_STATS(isolate(), LoadIC_SlowStub);
-      return slow_stub();
+      TRACE_HANDLER_STATS(isolate(), LoadIC_LoadIntegerIndexedExoticDH);
+      return LoadHandler::LoadNonExistent(isolate());
     case LookupIterator::ACCESS_CHECK:
     case LookupIterator::JSPROXY:
     case LookupIterator::NOT_FOUND: