ColorPropTypes support for isRequired and more precise description

Summary:
The previous implementation of ColorPropType was very hacky as it used `ReactPropTypes.oneOfType([colorValidator, ReactPropTypes.number])`. It turns out that oneOfType also accepts arbitrary functions instead of a type, but doesn't display any of the error message.

In this diff I properly implement isRequired (sadly we don't export `createChainableTypeChecker` in ReactPropTypes) and provide a lot more context that we have. I copy and pasted the way we displayed this context from the existing checkers.

**Test Plan**

When doing .isRequired and do not provide the value:

![simulator screen shot feb 1 2016 9 56 00 am](https://cloud.githubusercontent.com/assets/197597/12726239/61243f88-c8cb-11e5-889b-6594ffd85973.png)

When providing a bad value:

![simulator screen shot feb 1 2016 10 01 25 am](https://cloud.githubusercontent.com/assets/197597/12726244/6e80aa36-c8cb-11e5-9bd3-a8637de75496.png)
Closes facebook#5671

Reviewed By: svcscm

Differential Revision: D2886760

Pulled By: vjeux

fb-gh-sync-id: d6be42b5768fca5463fe80fe4b144506d21b0832

Libraries/StyleSheet/ColorPropType.js

@@ -11,12 +11,20 @@
 'use strict';
 
 var ReactPropTypes = require('ReactPropTypes');
+var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 
 var normalizeColor = require('normalizeColor');
 
-var ColorPropType = function(props, propName) {
+var colorPropType = function(isRequired, props, propName, componentName, location, propFullName) {
   var color = props[propName];
   if (color === undefined || color === null) {
+    if (isRequired) {
+      var locationName = ReactPropTypeLocationNames[location];
+      return new Error(
+        'Required ' + locationName + ' `' + (propFullName || propName) +
+        '` was not specified in `' + componentName + '`.'
+      );
+    }
     return;
   }
 
@@ -28,8 +36,11 @@ var ColorPropType = function(props, propName) {
   }
 
   if (normalizeColor(color) === null) {
+    var locationName = ReactPropTypeLocationNames[location];
     return new Error(
-`Invalid color supplied to ${propName}: ${color}. Valid color formats are
+      'Invalid ' + locationName + ' `' + (propFullName || propName) +
+      '` supplied to `' + componentName + '`: ' + color + '\n' +
+`Valid color formats are
   - #f0f (#rgb)
   - #f0fc (#rgba)
   - #ff00ff (#rrggbb)
@@ -39,8 +50,12 @@ var ColorPropType = function(props, propName) {
   - hsl(360, 100%, 100%)
   - hsla(360, 100%, 100%, 1.0)
   - transparent
-  - red`);
+  - red
+`);
   }
 };
 
+var ColorPropType = colorPropType.bind(null, false /* isRequired */);
+ColorPropType.isRequired = colorPropType.bind(null, true /* isRequired */);
+
 module.exports = ColorPropType;