Summary:
**Problem:**
As I was trying to document what color formats we supported, I realized that our current implementation based on the open source project tinycolor supported some crazy things. A few examples that were all valid:
```
tinycolor('abc')
tinycolor(' #abc ')
tinycolor('##abc')
tinycolor('rgb 255 0 0')
tinycolor('RGBA(0, 1, 2)')
tinycolor('rgb (0, 1, 2)')
tinycolor('hsv(0, 1, 2)')
tinycolor({r: 10, g: 10, b: 10})
tinycolor('hsl(1%, 2, 3)')
tinycolor('rgb(1.0, 2.0, 3.0)')
tinycolor('rgb(1%, 2%, 3%)')
```
The integrations of tinycolor were also really bad. processColor added "support" for pure numbers and an array of colors!?? ColorPropTypes did some crazy trim().toString() and repeated a bad error message twice.
**Solution:**
While iteratively cleaning the file, I eventually ended up reimplementing it entierly. Major changes are:
- The API is now dead simple: returns null if it doesn't parse or returns the int32 representation of the color
- Stricter parsing of at
Closes https://github.com/facebook/react-native/pull/5529
Reviewed By: svcscm
Differential Revision: D2872015
Pulled By: nicklockwood
fb-gh-sync-id: df78244eefce6cf8e8ed2ea51f58d6b232de16f9
