implement basic interface for pointer type on top of DataView

shim.js

@@ -0,0 +1,39 @@
+DataView.prototype.add = function (offset) {
+  return new DataView(this.buffer, offset);
+};
+DataView.prototype.writeU8 = function (val) {
+  return this.setUint8(0, val);
+};
+DataView.prototype.writeU16 = function (val) {
+  return this.setUint16(0, val);
+};
+DataView.prototype.writeU32 = function (val) {
+  return this.setUint32(0, val);
+};
+DataView.prototype.writeU64 = function (val) {
+  return this.setUint64(0, val);
+};
+DataView.prototype.readU8 = function () {
+  return this.getUint8(0);
+};
+DataView.prototype.readU16 = function () {
+  return this.getUint16(0);
+};
+DataView.prototype.readU32 = function () {
+  return this.getUint32(0);
+};
+DataView.prototype.readU64 = function () {
+  return this.getUint64(0);
+};
+DataView.prototype.writeByteArray = function (arr) {
+  for (let i = 0; i < (arr.byteLength || arr.length); i++) {
+    this.setUint8(i, arr[i]);
+  }
+};
+DataView.prototype.readByteArray = function (len) {
+  let ret = new DataView(new ArrayBuffer(len));
+  for (let i = 0; i < len; i++) {
+    ret.setUint8(i, this.getUint8(i));
+  }
+  return ret;
+};