Keep (Heap)TerminatedArray in a consistent state while building.

third_party/WebKit/Source/platform/heap/HeapTest.cpp

Index: third_party/WebKit/Source/platform/heap/HeapTest.cpp
diff --git a/third_party/WebKit/Source/platform/heap/HeapTest.cpp b/third_party/WebKit/Source/platform/heap/HeapTest.cpp
index 4d7a95459258d722b8df3c3765488b0436d03a09..a981e608582bc86bfc7da581004fbbde014010ef 100644
--- a/third_party/WebKit/Source/platform/heap/HeapTest.cpp
+++ b/third_party/WebKit/Source/platform/heap/HeapTest.cpp
@@ -4343,6 +4343,7 @@ TEST(HeapTest, HeapTerminatedArray)
     {
         HeapTerminatedArrayBuilder<TerminatedArrayItem> builder(arr);
         builder.grow(prefixSize);
+        conservativelyCollectGarbage();
         for (size_t i = 0; i < prefixSize; i++)
             builder.append(TerminatedArrayItem(IntWrapper::create(i)));
         arr = builder.release();