Fix up source map urls.

Review URL: https://chromiumcodereview.appspot.com//12217150
Adds support for Observable objects in web_ui.
This includes @observable annotation for automatic transformation by DWC. It also includes ObservableList/Map/Set types.

Observables use a batch-notification system where changes are queued up and sent to the handler during the "next microtask". This is similar to ES7 Object.observe proposal.

We don't have detailed change records yet but I plan to work on that in a follow up change. Keep that in mind when reviewing ObservableList/Map/Set types because they're in for an overhaul. The CL for that isn't ready but for comparison purposes you can find it here: https://chromiumcodereview.appspot.com/12096106/

All tests have been converted. Since I had to go through every single test, I took the liberty of removing incorrect <title> attributes throughout.

I still need to convert the MDV and explainer examples. I'm also interested in more perf tests. I'll work on that now, but would prefer not expanding the scope of this (already big) change :)

Feature request: https://github.com/dart-lang/web-ui/issues/259

Review URL: https://chromiumcodereview.appspot.com//12225039
Adds one-time final bindings.

Review URL: https://chromiumcodereview.appspot.com//12257024
template elements display:none in global stylesheet
This (roughly) matches the spec.

Review URL: https://chromiumcodereview.appspot.com//12212182
Ensure we don't add duplicate imports.

Review URL: https://chromiumcodereview.appspot.com//12253039
Add support for trimming and compacting text to help indent inside components.
To use this feature you must opt-in by adding an attribute to the template-tag
of a component (that's the only place where it is supported). See the test in
this CL for an example.

Review URL: https://chromiumcodereview.appspot.com//12207182
Generating appropriate source maps. This combines the power of edit-transactions
and code printers!

Review URL: https://chromiumcodereview.appspot.com//12271011
fixes for latest SDK, 0.3.6.2_r18539

* Url.isAbsolute() -> isAbsolute.
* API changes on Element
* remove some imports/exports were confusing analyzer

Review URL: https://chromiumcodereview.appspot.com//12260053
regenerate html setters

Review URL: https://chromiumcodereview.appspot.com//12207196
Fixes to get html offsets working also.

Review URL: https://chromiumcodereview.appspot.com//12256053
add @observable to editable_label and todo_row

todo_row doesn't strictly need it, but seems good practice since "todo" is using data binding.
I left it off router_options because it has no fields.

Review URL: https://chromiumcodereview.appspot.com//12212209
More fixes for the latest sdk. Just yesterday we got a few more breaking
changes in dart:html.

Review URL: https://chromiumcodereview.appspot.com//12290011
update version, fixes 366
Updates to webui for sdk 0.3.7+5

Review URL: https://chromiumcodereview.appspot.com//12288051
Update change log

Review URL: https://chromiumcodereview.appspot.com//12218170
fix typo ("Liscence" -> "Licence")
Update the license text. We got permission to redistribute that part of the code
before, but we forgot to update the licence file here.

Review URL: https://chromiumcodereview.appspot.com//12288066
fixes #367 - we need to replace imports in the code buffer, not just in the AST

Review URL: https://chromiumcodereview.appspot.com//12300039
Call postMessage synchronously
It seems to work out okay, because setImmediate in observers fires first.

I also like that it makes the test guarantees stronger: observers should never be slower than (i.e. happen after) postMessage.

Review URL: https://chromiumcodereview.appspot.com//12314002
Depend on the old analyzer temporarily.

Review URL: https://chromiumcodereview.appspot.com//12321003