Enhance jsc beautification

[tjhart]

An attempt ad addressing #2 , and also dealing with JSC stack trace entries with a '-1' line number.

I'm open to suggestions.

For example:

TypeError: undefined is not an object (evaluating 'Object.keys(t[n])')

This error is located at:
    in C
    in RCTView
    in p
    in _
    in p
    in RCTView
    in RCTView
    in RCTView
    in u
    in RCTView
    in u
    in C
    in n
    in E
    in RCTView
    in n
    in RCTView
    in u
    in PanGestureHandler
    in n
    in L
    in RCTView
    in n
    in t
    in P
    in v
    in p
    in RCTView
    in RCTView
    in l
    in RCTView
    in n
    in RCTView
    in u
    in RCTView
    in u
    in PanGestureHandler
    in n
    in S
    in P
    in P
    in _
    in s
    in n
    in h
    in RCTView
    in RCTView
    in c, stack:
keys@-1
<unknown>@290:1418
forEach@-1
value@290:1373
C@1512:523
Sn@90:30120
Or@90:45887
na@90:72881
ra@90:73371
Oa@90:80972
Wa@90:80310
Ue@90:83367
De@90:13673
notify@596:871
notifyNestedSubs@596:443
notifySubscribers@593:1112
<unknown>@-1
handleChangeWrapper@596:518
<unknown>@-1
j@605:4370
<unknown>@957:9704
<unknown>@1067:741
onPress@1541:1667
<unknown>@144:2232
value@28:3600
<unknown>@28:1144
value@28:2565
value@28:1114
value@-1

[tjhart]

Following up on this PR. I'm open to a more detailed conversation about the intent if you like.

@kmagiera , you seem to have written most of it. What are the next steps?

[tjhart]

Following up again. I'd rather not create a private fork of this, but I may have to.

@kmagiera are there any concerns with the PR? If so I'm happy to work with you to address them.

[pivey]

I'm in a situation where I could use this fix, would it be possible to merge this branch?