Implement calls to 'super()' (#445)

tests/compiler/call-super.ts

@@ -0,0 +1,66 @@
+import "allocator/arena";
+
+class A {
+  a: i32 = 1;
+  constructor() {
+    assert(this.a == 1);
+  }
+}
+
+class B extends A {
+  // a: i32 = 3; // FIXME: currently duplicate identifier
+  b: i32 = 2;
+  constructor() {
+    super();
+    assert(this.a == 1);
+    assert(this.b == 2);
+  }
+}
+
+function test1(): void {
+  var b = new B();
+  assert(b.a == 1);
+  assert(b.b == 2);
+}
+
+test1();
+
+class C {
+  a: i32 = 1;
+}
+
+class D extends C {
+  b: i32 = 2;
+  constructor() {
+    super();
+    assert(this.a == 1);
+    assert(this.b == 2);
+  }
+}
+
+function test2(): void {
+  var d = new D();
+  assert(d.a == 1);
+  assert(d.b == 2);
+}
+
+test2();
+
+class E {
+  a: i32 = 1;
+  constructor() {
+    assert(this.a == 1);
+  }
+}
+
+class F extends E {
+  b: i32 = 2;
+}
+
+function test3(): void {
+  var f = new F();
+  assert(f.a == 1);
+  // assert(f.b == 2); // FIXME: uses E#constructor, not initializing fields
+}
+
+test3();