* Property options have been updated to now include: `attribute`: set to explicitly false to not observe, to a string to customize name, or true or absent to observe lowercased name;   `type`: if a function, used to deserialize attribute value, otherwise can be an object with {fromAttribute: deserializing function, toAttribute: serializing function}; `reflect`: if true, property reflects to attribute using type.toAttribute if present; `shouldInvalidate`: function used to determine if a change should trigger invalidation.

* setting properties in update now does not trigger invalidation and does not issue a warning. This can and should be done to compute values before updating.

* finishUpdate has been added to perform post update tasks like direct dom manipulation. It is an async function which will be awaited before resolving the updateComplete promise. Setting properties in finishUpdate will trigger invalidation and this will finish before the updateComplete promise is resolved.
* no longer depends on polymer.

https://github.com/webcomponents/custom-elements/issues/167

* mark update/finishUpdate as abstract
* remove stack of promises in `invalidate`

Also test subclass/superclass do not improperly interact.

Uses `update` to update attributes and simplifies tracking.

* Convenience method for performing tasks after the element was first updated.
* Also makes presence of ShadyCSS optional.

…ssue.

This was deemed unnecessary meta-programming. For manual accessor creation, users can manage the value manually and call `invalidate` as an alternative to `set/getProperty`.

Fixes #146

Changes the `changedProperties` argument to `shouldUpdate`, `update`, and  `finishUpdate` to a Map.

Removes `_isReflectingProperty` and `_firstUpdateFinished` flags.

Avoids using Map constructor argument which is not supported on IE11.

* `createProperty` now takes a PropertyDeclaration and passes this on rather than having to look it up (optimization). Note, this means we now create properties for superClass properties. Also introduces a map used to store reflecting properties (optimization).
* correct `shouldInvalidate` property option so that it changes the property value but does not cause invalidation.
* renames `identity` to `notEqual` to reflect what it does.

Change made based on feedback that it seemed weird not to be able to just use `Boolean` as `type` and have the value serialize/deserialize as expected.

This method should be called in manually created property setters to trigger an invalidation and honor any configured property options for the given property.

* invalidate always completes in a microtask and should not be pushed out.
* properties set in `finishUpdate`are set after the next `updateComplete` resolves
* adds tests for customizing the timing of `updateComplete`

…ng. Fixes tests on Edge / IE.

This helps typescript users get a nice warning if they forget to implment `render`.

Fairly arcane, but looks like immediately invoking async function assigned to a getter that uses `super` loses `this` context on Safari 10 so working around by using Promises directly instead.

…into refactor

Add workaround for Promise timing bugs. Promise microtasks are not guaranteed to go before tasks.

Same issue as Polymer/polymer#5336.