[heap] Remove eager shortcut in JSFunction visitor.

This removes an optimization in the static JSFunction visitor that
eagerly marked through to the SharedFunctionInfo for code flushing
candidates. This causes all processing in VisitJSFunction to be
side-stepped and hence might cause leaks.

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/1476223002

Cr-Commit-Position: refs/heads/master@{#32332}

src/heap/objects-visiting-inl.h

@@ -464,14 +464,6 @@ void StaticMarkingVisitor<StaticVisitor>::VisitJSFunction(Map* map,
       // non-flushable, because it is required for bailing out from
       // optimized code.
       collector->code_flusher()->AddCandidate(function);
-      // Visit shared function info immediately to avoid double checking
-      // of its flushability later. This is just an optimization because
-      // the shared function info would eventually be visited.
-      SharedFunctionInfo* shared = function->shared();
-      if (StaticVisitor::MarkObjectWithoutPush(heap, shared)) {
-        StaticVisitor::MarkObject(heap, shared->map());
-        VisitSharedFunctionInfoWeakCode(heap, shared);
-      }
       // Treat the reference to the code object weakly.
       VisitJSFunctionWeakCode(map, object);
       return;