fixup! src: move v8 stats buffers out of Environment

Author: addaleax

src/node_v8.cc

@@ -30,6 +30,7 @@ namespace node {
 
 using v8::Array;
 using v8::ArrayBuffer;
+using v8::BackingStore;
 using v8::Context;
 using v8::FunctionCallbackInfo;
 using v8::HeapCodeStatistics;