remove unnecessary check

Author: gurgunday

lib/buffer.js

@@ -786,8 +786,6 @@ ObjectDefineProperty(Buffer.prototype, 'offset', {
 });
 
 Buffer.prototype.copy = function copy(target, targetStart, sourceStart, sourceEnd) {
-  if (!ArrayBufferIsView(this))
-    throw new ERR_INVALID_ARG_TYPE('source', ['Buffer', 'Uint8Array'], this);
   if (!ArrayBufferIsView(target))
     throw new ERR_INVALID_ARG_TYPE('target', ['Buffer', 'Uint8Array'], target);