Initial element access compilation; Carefully approaching std array

tests/compiler/std/array.ts

@@ -1 +1,75 @@
-// Array.fromPtr<i32>(1);
+var arr = changetype<i32[]>(Heap.allocate(sizeof<usize>() + 2 * sizeof<i32>()));
+
+assert(arr.length == 0);
+assert(arr.__capacity == 0);
+
+arr.push(42);
+
+assert(arr[0] == 42);
+assert(arr.length == 1);
+assert(arr.__capacity == 1);
+
+var i = arr.pop();
+
+assert(i == 42);
+assert(arr.length == 0);
+assert(arr.__capacity == 1);
+
+arr.push(43);
+
+assert(arr.length == 1);
+assert(arr.__capacity == 1);
+assert(arr[0] == 43);
+
+arr.push(44);
+
+assert(arr.length == 2);
+assert(arr.__capacity == 2);
+assert(arr[0] == 43);
+assert(arr[1] == 44);
+
+arr.push(45);
+
+assert(arr.length == 3);
+assert(arr.__capacity == 4);
+assert(arr[0] == 43);
+assert(arr[1] == 44);
+assert(arr[2] == 45);
+
+arr.unshift(42); // see FIXME in std:array
+
+assert(arr.length == 4);
+assert(arr.__capacity == 4);
+assert(arr[0] == 42);
+assert(arr[1] == 43);
+assert(arr[2] == 44);
+assert(arr[3] == 45);
+
+arr.unshift(41);
+
+assert(arr.length == 5);
+assert(arr.__capacity == 8);
+assert(arr[0] == 41);
+assert(arr[1] == 42);
+assert(arr[2] == 43);
+assert(arr[3] == 44);
+assert(arr[4] == 45);
+
+i = arr.shift();
+
+assert(i == 41);
+assert(arr.length == 4);
+assert(arr.__capacity == 8);
+assert(arr[0] == 42);
+assert(arr[1] == 43);
+assert(arr[2] == 44);
+assert(arr[3] == 45);
+
+i = arr.pop();
+
+assert(i == 45);
+assert(arr.length == 3);
+assert(arr.__capacity == 8);
+assert(arr[0] == 42);
+assert(arr[1] == 43);
+assert(arr[2] == 44);