Start monitoring uses of withContext, related to issue facebook#2112

Author: jimfb

src/core/ReactContext.js

@@ -12,6 +12,7 @@
 "use strict";
 
 var assign = require('Object.assign');
+var monitorCodeUse = require('monitorCodeUse');
 
 /**
  * Keeps track of the current context.
@@ -28,6 +29,9 @@ var ReactContext = {
   current: {},
 
   /**
+   *
+   * @deprecated
+   *
    * Temporarily extends the current context while executing scopedCallback.
    *
    * A typical use case might look like
@@ -44,6 +48,11 @@ var ReactContext = {
    * @return {ReactComponent|array<ReactComponent>}
    */
   withContext: function(newContext, scopedCallback) {
+
+    monitorCodeUse('react_with_context',
+      {newContext: newContext, scopedCallback: scopedCallback}
+    );
+
     var result;
     var previousContext = ReactContext.current;
     ReactContext.current = assign({}, previousContext, newContext);