Fall back to heap allocation in courgette alloc.

courgette/memory_allocator.h

Index: courgette/memory_allocator.h
diff --git a/courgette/memory_allocator.h b/courgette/memory_allocator.h
index 3f5143252102f973d0e61cfc4f6b1d1e37b8bb6f..dc1131da6975719e851b3b01682e470322f32c67 100644
--- a/courgette/memory_allocator.h
+++ b/courgette/memory_allocator.h
@@ -237,6 +237,10 @@ class MemoryAllocator {
         }
       }
     }
+    // If the above fails (e.g. because we are in a sandbox), just try the heap.
+    if (!mem && base::UncheckedMalloc(bytes, reinterpret_cast<void**>(&mem))) {
+      mem[0] = static_cast<uint8_t>(HEAP_ALLOCATION);
+    }
     return mem ? reinterpret_cast<pointer>(mem + sizeof(T)) : NULL;
   }