Update dart2js to fix #81.

test/kernel/regression/issue_000081.dart.txt

+library;
+import self as self;
+import "dart:core" as core;
+
+class Base extends core::Object {
+  field core::int hashCode;
+  constructor •() → self::Base
+    : self::Base::hashCode = 42, super core::Object::•();
+}
+class Sub extends self::Base {
+  field core::int _hashCode;
+  constructor •() → self::Sub
+    : self::Sub::_hashCode = null, super self::Base::•();
+  get hashCode() → dynamic
+    return let final dynamic #t1 = this._hashCode in #t1.==(null) ? this._hashCode = super.self::Base::hashCode : #t1;
+  method foo() → dynamic {
+    this._hashCode.==(null) ? this._hashCode = super.self::Base::hashCode : null;
+  }
+}
+static method main() → dynamic {
+  core::print(new self::Sub::•().hashCode);
+  dynamic l = <dynamic>[null];
+  let final dynamic #t2 = l in let final dynamic #t3 = 0 in #t2.[](#t3).==(null) ? #t2.[]=(#t3, "fisk") : null;
+}