buffer: make FastBuffer safe to construct

Using an explicit constructor is necessary to avoid relying on
`Array.prototype[Symbol.iterator]` and `%ArrayIteratorPrototype%.next`,
which can be mutated by users.

Author: aduh95

lib/internal/buffer.js

@@ -949,7 +949,14 @@ function writeFloatBackwards(val, offset = 0) {
   return offset;
 }
 
-class FastBuffer extends Uint8Array {}
+class FastBuffer extends Uint8Array {
+  // Using an explicit constructor here is necessary to avoid relying on
+  // `Array.prototype[Symbol.iterator]`, which can be mutated by users.
+  // eslint-disable-next-line no-useless-constructor
+  constructor(bufferOrLength, byteOffset, length) {
+    super(bufferOrLength, byteOffset, length);
+  }
+}
 
 function addBufferPrototypeMethods(proto) {
   proto.readBigUInt64LE = readBigUInt64LE;