revert "Inline dev-only requires (facebook#7188)"

Author: Keyan Zhang

src/isomorphic/classic/types/checkReactTypeSpec.js

@@ -11,6 +11,7 @@
 
 'use strict';
 
+var ReactComponentTreeDevtool = require('ReactComponentTreeDevtool');
 var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 var ReactPropTypesSecret = require('ReactPropTypesSecret');
 
@@ -73,7 +74,6 @@ function checkReactTypeSpec(typeSpecs, values, location, componentName, element,
         var componentStackInfo = '';
 
         if (__DEV__) {
-          var ReactComponentTreeDevtool = require('ReactComponentTreeDevtool');
           if (debugID !== null) {
             componentStackInfo = ReactComponentTreeDevtool.getStackAddendumByID(debugID);
           } else if (element !== null) {

src/renderers/shared/stack/reconciler/ReactChildReconciler.js

@@ -11,6 +11,7 @@
 
 'use strict';
 
+var ReactComponentTreeDevtool = require('ReactComponentTreeDevtool');
 var ReactReconciler = require('ReactReconciler');
 
 var instantiateReactComponent = require('instantiateReactComponent');
@@ -23,7 +24,6 @@ function instantiateChild(childInstances, child, name, selfDebugID) {
   // We found a component instance.
   var keyUnique = (childInstances[name] === undefined);
   if (__DEV__) {
-    var ReactComponentTreeDevtool = require('ReactComponentTreeDevtool');
     warning(
       keyUnique,
       'flattenChildren(...): Encountered two children with the same key, ' +