Node.js Buffer should be useable as a Uint8Array and is missing a constructor (#8919)

* make NodeBuffer extend Uint8Array

* add missing Buffer(ArrayBuffer) constructor

* add TODOs for missing Buffer methods

node/node-tests.ts

@@ -138,6 +138,7 @@ function bufferTests() {
     var base64Buffer = new Buffer('','base64');
     var octets: Uint8Array = null;
     var octetBuffer = new Buffer(octets);
+    var sharedBuffer = new Buffer(octets.buffer);
     var copiedBuffer = new Buffer(utf8Buffer);
     console.log(Buffer.isBuffer(octetBuffer));
     console.log(Buffer.isEncoding('utf8'));
@@ -181,6 +182,12 @@ function bufferTests() {
         let sb = new ImportedSlowBuffer(43);
         b.writeUInt8(0, 6);
     }
+
+    // Buffer has Uint8Array's buffer field (an ArrayBuffer).
+    {
+      let buffer = new Buffer('123');
+      let octets = new Uint8Array(buffer.buffer);
+    }
 }