Avoid unnecessary global lookups of testingExposeCycleCount

Author: ajklein

src/observe.js

@@ -15,6 +15,8 @@
 (function(global) {
   'use strict';
 
+  var testingExposeCycleCount = global.testingExposeCycleCount;
+
   // Detect and do basic sanity checking on Object/Array.observe.
   function detectObjectObserve() {
     if (typeof Object.observe !== 'function' ||
@@ -446,7 +448,7 @@
     while (cycles < MAX_DIRTY_CHECK_CYCLES && observer.check_()) {
       cycles++;
     }
-    if (global.testingExposeCycleCount)
+    if (testingExposeCycleCount)
       global.dirtyCheckCycleCount = cycles;
 
     return cycles > 0;
@@ -845,7 +847,7 @@
         anyChanged = true;
     } while (cycles < MAX_DIRTY_CHECK_CYCLES && anyChanged);
 
-    if (global.testingExposeCycleCount)
+    if (testingExposeCycleCount)
       global.dirtyCheckCycleCount = cycles;
 
     runningMicrotaskCheckpoint = false;

tests/index.html

@@ -21,7 +21,10 @@
 <link rel="stylesheet" href="../node_modules/mocha/mocha.css">
 <script src="../node_modules/chai/chai.js"></script>
 <script src="../node_modules/mocha/mocha.js"></script>
+
+<script>window.testingExposeCycleCount = true</script>
 <script src="../src/observe.js"></script>
+
 <script>
 mocha.setup({
   ui: 'tdd',

tests/test.js

@@ -16,8 +16,6 @@ var observer;
 var callbackArgs = undefined;
 var callbackInvoked = false;
 
-window.testingExposeCycleCount = true;
-
 function then(fn) {
   setTimeout(function() {
     Platform.performMicrotaskCheckpoint();