Update index.js

Splice too much？
Merge pull request #511 from zxc122333/patch-1

Fix splicing error in Observer
minor formatting
fix #517 v-model[number] initial value
batcher allow duplicate id if the job is pushed during flush
trigger binding notify in the same order they are added
fix #512 attribute interpolation with filters
rename v-model default handler
add v-model read only filter warning
fix ci tasks
update firebase version in example
fix #520 let watchers handle callbacks that trigger removeCb()
destroy component after leaving transition
make owner vm the context for js transition hooks
document transition hook context
fix #531 content fallback with multiple insertion points
fix #539 v-if duplicate compile when a different truthy value is set
fix IE+SVG no classList available error. Based on #537 by @tyage
fix api/child unit test in IE
fix #536 v-ref lost after transition