Fix function declaration in if statement (#6963)

Firefox doesn't like these and throws.
(cherry picked from commit 3c3c30a19a)

.eslintrc.js

@@ -30,6 +30,7 @@ module.exports = {
     'indent': [ERROR, 2, {SwitchCase: 1}],
     'jsx-quotes': [ERROR, 'prefer-double'],
     'no-bitwise': OFF,
+    'no-inner-declarations': [ERROR, 'functions'],
     'no-multi-spaces': ERROR,
     'no-restricted-syntax': [ERROR, 'WithStatement'],
     'no-shadow': ERROR,

scripts/bench/extract-component.js

@@ -112,7 +112,7 @@ function print(outerComponent) {
         var values = keys.map((childKey) => renderedChildren[childKey]);
 
         if (keys.length) {
-          function dump(children) {
+          var dump = function(children) {
             if (typeof children === 'boolean' || children == null) {
               return '' + children;
             }
@@ -130,7 +130,7 @@ function print(outerComponent) {
               debugger;
               throw new Error('hmm');
             }
-          }
+          };
 
           markup += '\n';
           var children = element.props.children;

src/isomorphic/classic/element/ReactElement.js

@@ -210,7 +210,7 @@ ReactElement.createElement = function(type, config, children) {
       type;
 
     // Create dummy `key` and `ref` property to `props` to warn users against its use
-    function warnAboutAccessingKey() {
+    var warnAboutAccessingKey = function() {
       if (!specialPropKeyWarningShown) {
         specialPropKeyWarningShown = true;
         warning(
@@ -223,10 +223,10 @@ ReactElement.createElement = function(type, config, children) {
         );
       }
       return undefined;
-    }
+    };
     warnAboutAccessingKey.isReactWarning = true;
 
-    function warnAboutAccessingRef() {
+    var warnAboutAccessingRef = function() {
       if (!specialPropRefWarningShown) {
         specialPropRefWarningShown = true;
         warning(
@@ -239,7 +239,7 @@ ReactElement.createElement = function(type, config, children) {
         );
       }
       return undefined;
-    }
+    };
     warnAboutAccessingRef.isReactWarning = true;
 
     if (typeof props.$$typeof === 'undefined' ||