Type Synthetic{Keyboard,Mouse}Event.getModifierState
Type Synthetic{Keyboard,Mouse}Event.getModifierState

Summary:
I noticed `SyntheticKeyboardEvent.getModifierState` was uncovered because it was typed as any
Update the react-dom lib def to match the typing from dom
Also included `SyntheticMouseEvent.getModifierState`
diffusion/FBS/browse/master/fbcode/flow/lib/dom.js$327,419

Reviewed By: jbrown215

Differential Revision: D13822492

fbshipit-source-id: 30909c5cc7b34013a117993a714c87775110420a

mroch/flow,facebook/flow,facebook/flow,facebook/flow,mroch/flow,popham/flow,popham/flow,mroch/flow,popham/flow,popham/flow,samwgoldman/flow,mroch/flow,mroch/flow,facebook/flow,samwgoldman/flow,gabelevi/flow,samwgoldman/flow,mroch/flow,mroch/flow,samwgoldman/flow,popham/flow,facebook/flow,facebook/flow,gabelevi/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,gabelevi/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,popham/flow,popham/flow,facebook/flow,samwgoldman/flow