Revert "[modules] Temporarily disable IC support for namespace accesses"

This reverts commit fbe184a6.

Reason for revert: Baseline performance test score established, re-enabling feature.

Original change's description:
> [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/639057
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47753}

TBR=adamk@chromium.org,jkummerow@chromium.org

Change-Id: Ia92e3247bc594e2fa6c937d379fa172244df2d8a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/647966Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47775}

src/ic/ic.cc

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