Fix several bugs in compaction:

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 62323bafe104a1bd1f5fd68d548a784fa7e6c641..8e7a947f171e86b7693bc682f71ed702e9644980 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -2020,8 +2020,13 @@ void PagedSpace::EvictEvacuationCandidatesFromFreeLists() {
   if (allocation_info_.top >= allocation_info_.limit) return;
 
   if (Page::FromAddress(allocation_info_.top)->IsEvacuationCandidate()) {
-      allocation_info_.top = NULL;
-      allocation_info_.limit = NULL;
+    // Create filler object to keep page iterable if it was iterable.
+    int remaining =
+        static_cast<int>(allocation_info_.limit - allocation_info_.top);
+    heap()->CreateFillerObjectAt(allocation_info_.top, remaining);
+
+    allocation_info_.top = NULL;
+    allocation_info_.limit = NULL;
   }
 }