Enable heap compaction on all 'container' arenas.

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

Index: third_party/WebKit/Source/platform/heap/HeapPage.cpp
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.cpp b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
index 2d1b043d3a5271d177d73f9b56d0a5fe14ce4ec9..d632988f0987021f7a9111030195c8b57365c5c3 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.cpp
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
@@ -504,10 +504,15 @@ void NormalPageArena::SweepAndCompact() {
     normal_page->SweepAndCompact(context);
   }
 
+  // All pages were empty; nothing to compact.
+  if (!context.current_page_) {
+    heap.Compaction()->FinishedArenaCompaction(this, 0, 0);
+    return;
+  }
+
   size_t freed_size = 0;
   size_t freed_page_count = 0;
 
-  DCHECK(context.current_page_);
   // If the current page hasn't been allocated into, add it to the available
   // list, for subsequent release below.
   size_t allocation_point = context.allocation_point_;