blink/heap: remove spurious ShrinkVector change

Looks like some extra code was introduced to HeapTest.ShrinkVector in
ee337661 that likely wasn't meant to be.

Change-Id: Ief988a083881a95bf1bbcdf6cacba29aabf1c480
Reviewed-on: https://chromium-review.googlesource.com/c/1352155Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611120}

third_party/blink/renderer/platform/heap/heap_test.cc

@@ -6782,14 +6782,6 @@ TEST(HeapTest, PromptlyFreeStackAllocatedHeapLinkedHashSet) {
 }
 
 TEST(HeapTest, ShrinkVector) {
-  HashMap<int, int> a;
-  a.insert(1, 2);
-  HashMap<int, int> b;
-  b = std::move(a);
-  a.clear();
-  LOG(ERROR) << "a.size() " << a.size();
-  LOG(ERROR) << "b.size() " << b.size();
-
   // Regression test: https://crbug.com/823289
 
   HeapVector<Member<IntWrapper>> vector;