[modules] Temporarily disable IC support for namespace accesses

To get a proper performance baseline after fixing the perf tests in
https://chromium-review.googlesource.com/c/v8/v8/+/639396.

This is intended to be reverted after a couple of hours.

Change-Id: If36e4bfa5bd113599652f5c2016f886533af2746
Reviewed-on: https://chromium-review.googlesource.com/639057Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47753}

src/ic/ic.cc

@@ -1020,7 +1020,9 @@ Handle<Object> LoadIC::GetMapIndependentHandler(LookupIterator* lookup) {
         FieldIndex index = FieldIndex::ForInObjectOffset(object_offset, *map);
         return SimpleFieldLoad(isolate(), index);
       }
-      if (holder->IsJSModuleNamespace()) {
+      // TODO(jkummerow): Re-enable this after performance bots have
+      // picked up the baseline.
+      if (false && holder->IsJSModuleNamespace()) {
         Handle<ObjectHashTable> exports(
             Handle<JSModuleNamespace>::cast(holder)->module()->exports(),
             isolate());