add React.PropTypes.any

add the ability for React propTypes to accept an `any` type: `someProp: React.PropTypes.any`.
This is more useful when combined with `.isRequired`, to enforce that _something_ is passed:
`someProp: React.PropTypes.any.isRequired`

src/core/ReactPropTypes.js

@@ -87,12 +87,24 @@ var Props = {
   instanceOf: createInstanceTypeChecker,
 
   renderable: createRenderableTypeChecker(),
-  component: createComponentTypeChecker()
 
+  component: createComponentTypeChecker(),
+
+  any: createAnyTypeChecker()
 };
 
 var ANONYMOUS = '<<anonymous>>';
 
+function createAnyTypeChecker() {
+  function validateAnyType(
+    shouldThrow, propValue, propName, componentName, location
+  ) {
+    // always is valid
+    return true;
+  }
+  return createChainableTypeChecker(validateAnyType);
+}
+
 function isRenderable(propValue) {
   switch(typeof propValue) {
     case 'number':

src/core/__tests__/ReactPropTypes-test.js

@@ -347,4 +347,30 @@ describe('Union Types', function() {
     });
   });
 
+  describe('Any type', function() {
+    it('should should accept any value', function() {
+      expect(typeCheck(Props.any, 1)).not.toThrow();
+      expect(typeCheck(Props.any, 'str')).not.toThrow();
+      expect(typeCheck(Props.any.isRequired, 1)).not.toThrow();
+      expect(typeCheck(Props.any.isRequired, 'str')).not.toThrow();
+
+      expect(typeCheck(Props.any, null)).not.toThrow();
+      expect(typeCheck(Props.any, undefined)).not.toThrow();
+
+      expect(typeCheck(Props.any.isRequired, null)).toThrow(
+        'Invariant Violation: Required prop `testProp` was not specified in ' +
+        '`testComponent`.'
+      );
+      expect(typeCheck(Props.any.isRequired, undefined)).toThrow(
+        'Invariant Violation: Required prop `testProp` was not specified in ' +
+        '`testComponent`.'
+      );
+    });
+
+    it('should have a weak version that returns true/false', function() {
+      expect(typeCheck(Props.string.weak, null)()).toEqual(true);
+      expect(typeCheck(Props.any.weak.isRequired, null)()).toEqual(false);
+      expect(typeCheck(Props.any.isRequired.weak, null)()).toEqual(false);
+    });
+  });
 });