Element constructors

Element constructors

Elements with distinct types can now be constructed directly.

Example:
  var div = new DivElement();

There are many elements that cannot be created this way.  For example, the <b>bold</b> element is simply a HTMLElement with styling, not a separate subclass of HTMLElement.

Committed: https://code.google.com/p/dart/source/detail?r=7921

[vsm, 2012-05-23 04:46:06]

LGTM!

https://chromiumcodereview.appspot.com/10384024/diff/4003/tests/html/element_...
File tests/html/element_constructor_1_test.dart (right):

https://chromiumcodereview.appspot.com/10384024/diff/4003/tests/html/element_...
tests/html/element_constructor_1_test.dart:37: });
Minor nit: add a test for CanvasElement or some other type that has constructor
params.