As a last resort try to allocate out of the smaller size size-class in

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 50530a19572afec1f9fde0fa6e9a3a83fc4d6344..d477e15f6961d8b6c16113861d13ac2145c61030 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -2118,13 +2118,13 @@ FreeListNode* FreeListCategory::PickNodeFromList(int *node_size) {
 
   while (node != NULL &&
          Page::FromAddress(node->address())->IsEvacuationCandidate()) {
-    available_ -= node->Size();
+    available_ -= reinterpret_cast<FreeSpace*>(node)->Size();
     node = node->next();
   }
 
   if (node != NULL) {
     set_top(node->next());
-    *node_size = node->Size();
+    *node_size = reinterpret_cast<FreeSpace*>(node)->Size();
     available_ -= *node_size;
   } else {
     set_top(NULL);
@@ -2138,6 +2138,18 @@ FreeListNode* FreeListCategory::PickNodeFromList(int *node_size) {
 }
 
 
+FreeListNode* FreeListCategory::PickNodeFromList(int size_in_bytes,
+                                                 int *node_size) {
+  FreeListNode* node = PickNodeFromList(node_size);
+  if (node != NULL && *node_size < size_in_bytes) {
+    Free(node, *node_size);
+    *node_size = 0;
+    return NULL;
+  }
+  return node;
+}
+
+
 void FreeListCategory::Free(FreeListNode* node, int size_in_bytes) {
   node->set_next(top_);
   top_ = node;
@@ -2202,11 +2214,6 @@ int FreeList::Free(Address start, int size_in_bytes) {
   // Insert other blocks at the head of a free list of the appropriate
   // magnitude.
   if (size_in_bytes <= kSmallListMax) {
-    ASSERT(!owner_->ConstantAllocationSize() ||
-        (owner_->identity() == MAP_SPACE && size_in_bytes >= Map::kSize) ||
-        (owner_->identity() == CELL_SPACE && size_in_bytes >= Cell::kSize) ||
-        (owner_->identity() == PROPERTY_CELL_SPACE &&
-            size_in_bytes >= JSGlobalPropertyCell::kSize));
     small_list_.Free(node, size_in_bytes);
     page->add_available_in_small_free_list(size_in_bytes);
   } else if (size_in_bytes <= kMediumListMax) {
@@ -2229,13 +2236,13 @@ FreeListNode* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
   FreeListNode* node = NULL;
   Page* page = NULL;
 
-  if ((owner_->ConstantAllocationSize() && size_in_bytes <= kSmallListMax) ||
-      size_in_bytes <= kSmallAllocationMax) {
+  if (size_in_bytes <= kSmallAllocationMax) {
     node = small_list_.PickNodeFromList(node_size);
     if (node != NULL) {
       ASSERT(size_in_bytes <= *node_size);
       page = Page::FromAddress(node->address());
       page->add_available_in_small_free_list(-(*node_size));
+      ASSERT(IsVeryLong() || available() == SumFreeLists());
       return node;
     }
   }
@@ -2246,6 +2253,7 @@ FreeListNode* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
       ASSERT(size_in_bytes <= *node_size);
       page = Page::FromAddress(node->address());
       page->add_available_in_medium_free_list(-(*node_size));
+      ASSERT(IsVeryLong() || available() == SumFreeLists());
       return node;
     }
   }
@@ -2256,6 +2264,7 @@ FreeListNode* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
       ASSERT(size_in_bytes <= *node_size);
       page = Page::FromAddress(node->address());
       page->add_available_in_large_free_list(-(*node_size));
+      ASSERT(IsVeryLong() || available() == SumFreeLists());
       return node;
     }
   }
@@ -2298,10 +2307,37 @@ FreeListNode* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
   if (huge_list_.top() == NULL) {
     huge_list_.set_end(NULL);
   }
-
   huge_list_.set_available(huge_list_available);
-  ASSERT(IsVeryLong() || available() == SumFreeLists());
 
+  if (node != NULL) {
+    ASSERT(IsVeryLong() || available() == SumFreeLists());
+    return node;
+  }
+
+  if (size_in_bytes <= kSmallListMax) {
+    node = small_list_.PickNodeFromList(size_in_bytes, node_size);
+    if (node != NULL) {
+      ASSERT(size_in_bytes <= *node_size);
+      page = Page::FromAddress(node->address());
+      page->add_available_in_small_free_list(-(*node_size));
+    }
+  } else if (size_in_bytes <= kMediumListMax) {
+    node = medium_list_.PickNodeFromList(size_in_bytes, node_size);
+    if (node != NULL) {
+      ASSERT(size_in_bytes <= *node_size);
+      page = Page::FromAddress(node->address());
+      page->add_available_in_medium_free_list(-(*node_size));
+    }
+  } else if (size_in_bytes <= kLargeListMax) {
+    node = large_list_.PickNodeFromList(size_in_bytes, node_size);
+    if (node != NULL) {
+      ASSERT(size_in_bytes <= *node_size);
+      page = Page::FromAddress(node->address());
+      page->add_available_in_large_free_list(-(*node_size));
+    }
+  }
+
+  ASSERT(IsVeryLong() || available() == SumFreeLists());
   return node;
 }