Merge tag 'v0.12.2' into develop

0.12.2
Fixed the validator tests.
Added getErrorsFor to the validator.
Added speculativelyValidateFragment to validator.
Added support for deleting elements with DELETE.
Added tests for validation error UI.
Fixed a problem with navigating to error markers.
Fixed a bug in possibleWhere.
Better description of the Bootstrap bug.
Text nodes were passing the wrong node to _processEventResult.
Updated dependencies.
Doc for upcoming version.
Version bump.
Changes to work around a Firefox bug.

The recent changes to wed triggered this Firefox bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=969773

The `_blur` method now calls `_caretChangeEmitter` so as to avoid
focusing again, which would be the right thing to do in any case, but
happens to make the bug go away.
A few changes to get the test suite to pass on Firefox.
Added support for Command key on OS X.
Keep the window height intact.
More information regarding support.
Document the changes.
Merge branch 'release/0.13.0'