Fix test server paths to include observe-js
Merge pull request #248 from azakus/fix-grunt-tests

Fix grunt tests
Replace SideTable with WeakMap
Merge pull request #249 from arv/weak-map

Replace SideTable with WeakMap
Fix insertBefore for IE10.

In `insertBefore(node, undefined)`, `undefined` is not treated as
`null` causing a runtime error.
Make sure we do not remove the shadow dom of nested hosts.
Merge pull request #251 from arv/issue-245-dont-clear-inner-shadows

Make sure we do not remove the shadow dom of nested hosts.
No need to associate node with renderer just to remove stale child nodes.
Merge pull request #252 from arv/remove-useless-associate-node

No need to associate node with renderer just to remove stale child nodes
Change from using a WeakMap to use expando
Update CONTRIBUTING.md

Polymer/polymer#273
remove tools submodule
Merge pull request #253 from arv/less-weak-maps

Change from using a WeakMap to use expando
test: increase mocha timeout
README: event objects are wrapped now

Fixes https://github.com/Polymer/docs/issues/149
Call nodeWasAdded on all the nodes in the added tree.
Merge pull request #256 from arv/distributed-nodes-again

Call nodeWasAdded on all the nodes in the added tree.
log the exception stack if available
Merge pull request #261 from morethanreal/master

log the exception stack if available
Fix issue with syncing render nodes