Adding polyfill support for custom elements.

Adding polyfill support for custom elements.

BUG=
R=jmesserly@google.com

Committed: https://code.google.com/p/dart/source/detail?r=26405

[Jennifer Messerly, 2013-08-20 19:09:59]

https://codereview.chromium.org/22967006/diff/6006/tests/html/custom_elements...
File tests/html/custom_elements_test.dart (right):

https://codereview.chromium.org/22967006/diff/6006/tests/html/custom_elements...
tests/html/custom_elements_test.dart:58: useHtmlIndividualConfiguration();
does this need to be individual config? it slows things down

https://codereview.chromium.org/22967006/diff/11001/pkg/custom_element/lib/cu...
File pkg/custom_element/lib/custom-elements.debug.js (right):

https://codereview.chromium.org/22967006/diff/11001/pkg/custom_element/lib/cu...
pkg/custom_element/lib/custom-elements.debug.js:1: // Copyright (c) 2012 The
Polymer Authors. All rights reserved.
from the comment on earlier CL's, should this be named:

    custom_element.js
    custom_element.min.js

basically, no "debug" and also use underscores to match Dart file naming
conventions. (Shadow DOM pkg also uses underscores. It uses .debug too, but I
think we were going to fix that...)

https://codereview.chromium.org/22967006/diff/11001/tests/html/custom_element...
File tests/html/custom_elements_test.dart (right):

https://codereview.chromium.org/22967006/diff/11001/tests/html/custom_element...
tests/html/custom_elements_test.dart:40: if (!document.supportsRegister) {
this doesn't need mutation observers?

https://codereview.chromium.org/22967006/diff/11001/tools/dom/templates/html/...
File tools/dom/templates/html/impl/impl_Element.darttemplate (right):

https://codereview.chromium.org/22967006/diff/11001/tools/dom/templates/html/...
tools/dom/templates/html/impl/impl_Element.darttemplate:1181: // Polyfill relies
on mutation observers for upgrading, but we want it
Interesting that the polyfill works this way... do we have an issue or bug
number on the Polymer side we can reference?

does upgrade happen synchronously in other places, such as `new Element.tag` and
`clone`?

[blois, 2013-08-20 19:36:55]

https://codereview.chromium.org/22967006/diff/11001/pkg/custom_element/lib/cu...
File pkg/custom_element/lib/custom-elements.debug.js (right):

https://codereview.chromium.org/22967006/diff/11001/pkg/custom_element/lib/cu...
pkg/custom_element/lib/custom-elements.debug.js:1: // Copyright (c) 2012 The
Polymer Authors. All rights reserved.
On 2013/08/20 19:09:59, John Messerly wrote:
> from the comment on earlier CL's, should this be named:
> 
>     custom_element.js
>     custom_element.min.js
> 
> basically, no "debug" and also use underscores to match Dart file naming
> conventions. (Shadow DOM pkg also uses underscores. It uses .debug too, but I
> think we were going to fix that...)

My goal was that the file can be copied over from Polymer with no modifications-
naming style is from their file. The .debug portion is because the unadorned
name is the version which uses the loaders.

https://codereview.chromium.org/22967006/diff/11001/tests/html/custom_element...
File tests/html/custom_elements_test.dart (right):

https://codereview.chromium.org/22967006/diff/11001/tests/html/custom_element...
tests/html/custom_elements_test.dart:40: if (!document.supportsRegister) {
On 2013/08/20 19:09:59, John Messerly wrote:
> this doesn't need mutation observers?

It  does, they are included in the file. Per-polyfill scripts probably do not
work well with overlapping dependencies.

https://codereview.chromium.org/22967006/diff/11001/tools/dom/templates/html/...
File tools/dom/templates/html/impl/impl_Element.darttemplate (right):

https://codereview.chromium.org/22967006/diff/11001/tools/dom/templates/html/...
tools/dom/templates/html/impl/impl_Element.darttemplate:1181: // Polyfill relies
on mutation observers for upgrading, but we want it
On 2013/08/20 19:09:59, John Messerly wrote:
> Interesting that the polyfill works this way... do we have an issue or bug
> number on the Polymer side we can reference?
> 
> does upgrade happen synchronously in other places, such as `new Element.tag`
and
> `clone`?
> 
It's synchronous in clone and document.createElement but for some reason (not
sure why), innerHTML does not upgrade- it waits for the sub-tree to be added to
the document then gets upgraded by mutation observers. It could be a polyfill
limitation.

If innerHtml is rare then we could require users explicitly upgrade if they need
synchronous behavior.

[Jennifer Messerly, 2013-08-20 21:58:43]

thanks Pete, it all makes sense. LGTM

[blois, 2013-08-20 22:56:15]

Committed patchset #3 manually as r26405 (presubmit successful).