Log unknown props only when we have a match

Logging every unknown property got very noisy when combined with use of `transferPropsTo`. I knew this would be a potential issue initially but decided it was worth it. Others disagreed and it's resulting in some confusion.

This changes the logging to ensure that we have a potential correction, so only DOMish properties should result in warnings.

src/dom/DOMPropertyOperations.js

@@ -44,17 +44,20 @@ if (__DEV__) {
     }
 
     warnedProperties[name] = true;
-    var message = 'Unknown DOM property ' + name + '.';
     var lowerCasedName = name.toLowerCase();
 
     // data-* attributes should be lowercase; suggest the lowercase version
     var standardName = DOMProperty.isCustomAttribute(lowerCasedName) ?
       lowerCasedName : DOMProperty.getPossibleStandardName[lowerCasedName];
+
+    // For now, only warn when we have a suggested correction. This prevents
+    // logging too much when using transferPropsTo.
     if (standardName != null) {
-      message += ' Did you mean ' + standardName + '?';
+      console.warn(
+        'Unknown DOM property ' + name + '. Did you mean ' + standardName + '?'
+      );
     }
 
-    console.warn(message);
   };
 }
 

src/dom/__tests__/DOMPropertyOperations-test.js

@@ -151,24 +151,18 @@ describe('DOMPropertyOperations', function() {
 
   describe('injectDOMPropertyConfig', function() {
     it('should support custom attributes', function() {
-      spyOn(console, 'warn');
-
       // foobar does not exist yet
       expect(DOMPropertyOperations.createMarkupForProperty(
         'foobar',
         'simple'
       )).toBe(null);
 
-      expect(console.warn.argsForCall.length).toBe(1);
-
       // foo-* does not exist yet
       expect(DOMPropertyOperations.createMarkupForProperty(
         'foo-xyz',
         'simple'
       )).toBe(null);
 
-      expect(console.warn.argsForCall.length).toBe(2);
-
       // inject foobar DOM property
       DOMProperty.injection.injectDOMPropertyConfig({
         isCustomAttribute: function(name) {