Added MutationObserver
Merge pull request #35 from rinfield/topic/MutationObserver

Add MutationObserver
Fixed ArrayBuffer and DataView interfaces to better conform to specification

https://developer.mozilla.org/en-US/docs/Web/API/ArrayBuffer
https://developer.mozilla.org/en-US/docs/Web/API/DataView
https://www.khronos.org/registry/typedarray/specs/latest/#5
Merge pull request #36 from alejo90/TypedArrays

Fixed ArrayBuffer and DataView interfaces to better conform to specification