Add a .data pointer on ArrayBuffers for convenience, see #291

std/assembly/arraybuffer.ts

@@ -9,6 +9,9 @@ export class ArrayBuffer {
 
   readonly byteLength: i32; // capped to [0, MAX_LENGTH]
 
+  // @unsafe
+  get data(): usize { return changetype<usize>(this) + HEADER_SIZE; }
+
   constructor(length: i32, unsafe: bool = false) {
     if (<u32>length > <u32>MAX_BLENGTH) throw new RangeError("Invalid array buffer length");
     var buffer = allocateUnsafe(length);

std/assembly/index.d.ts

@@ -372,6 +372,8 @@ declare namespace table {
 declare class ArrayBuffer {
   /** The size, in bytes, of the array. */
   readonly byteLength: i32;
+  /** Unsafe pointer to the start of the data in memory. */
+  readonly data: usize;
   /** Constructs a new array buffer of the given length in bytes. */
   constructor(length: i32, unsafe?: bool);
   /** Returns a copy of this array buffer's bytes from begin, inclusive, up to end, exclusive. */