Improve findComponentRoot Error Message

Instead of simply logging the React ID of the `ancestorNode` when `findComponentRoot` fails, use a `try ... finally` to `console.error` the `ancestorNode`. This allows modern web inspectors to actually log a reference to the node (which may not have a React ID).

This means when people run into the problem, they will not have to execute:

  require('ReactID').getNode(<copy+paste>);

NOTE: Admittedly, this will not log anything in IE8. That's fine, since IE8 has shitty console logging anyway.

src/core/ReactInstanceHandles.js

@@ -296,12 +296,15 @@ var ReactInstanceHandles = {
       }
       child = child.nextSibling;
     }
+    global.console && console.error && console.error(
+      'Error while invoking `findComponentRoot` with the following ' +
+      'ancestor node:',
+      ancestorNode
+    );
     invariant(
       false,
-      'findComponentRoot: Unable to find element by React ID, `%s`. This ' +
-      'indicates that someone (or the browser) has mutated the DOM tree in ' +
-      'an unexpected way. Try inspecting the child nodes of the element with ' +
-      'React ID, `%s`.',
+      'findComponentRoot(..., %s): Unable to find element. This probably ' +
+      'means the DOM was unexpectedly mutated (e.g. by the browser).',
       id,
       ReactID.getID(ancestorNode)
     );

src/core/__tests__/ReactInstanceHandles-test.js

@@ -139,10 +139,9 @@ describe('ReactInstanceHandles', function() {
           ReactID.getID(childNodeB)
         );
       }).toThrow(
-        'Invariant Violation: findComponentRoot: Unable to find element by ' +
-        'React ID, `.react[0].1:0`. This indicates that someone (or the ' +
-        'browser) has mutated the DOM tree in an unexpected way. Try ' +
-        'inspecting the child nodes of the element with React ID, `.react[0]`.'
+        'Invariant Violation: findComponentRoot(..., .react[0].1:0): Unable ' +
+        'to find element. This probably means the DOM was unexpectedly ' +
+        'mutated (e.g. by the browser).'
       );
     });
   });