[crankshaft] Fragmentation-free allocation folding.

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index 2a54b5a9ca9ce8ec42e48ed1b9457299c0352110..13622d6e046e59adf3ae13b15af36f757eb4e0d9 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -2486,7 +2486,8 @@ HeapObject* FreeList::Allocate(int size_in_bytes) {
                  new_node_size - size_in_bytes - linear_size);
     owner_->SetTopAndLimit(new_node->address() + size_in_bytes,
                            new_node->address() + size_in_bytes + linear_size);
-  } else if (bytes_left >= 0) {
+  } else {
+    DCHECK(bytes_left >= 0);
     // Normally we give the rest of the node to the allocator as its new
     // linear allocation area.
     owner_->SetTopAndLimit(new_node->address() + size_in_bytes,