[Files App] Override loadTimeData.getBoolean() in file_tasks_unittest.js

Override loadTimeData.getBoolean() instead of specifying
loadTimeData.data, in order to be consistent with other integration
tests.

BUG=912236
TEST=browser_tests --gtest_filter="Tasks/*"

Change-Id: Ib73d17082fb5da6909454cba5d765b9967e791f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2224892Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: François Degros <fdegros@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773939}

ui/file_manager/file_manager/foreground/js/file_tasks_unittest.js

@@ -58,17 +58,11 @@ const mockTaskHistory = /** @type {!TaskHistory} */ ({
   recordTaskExecuted: function(id) {},
 });
 
-/**
- * Load time data.
- */
-loadTimeData.data = {
-  'ZIP_NO_NACL': false,
-};
-
 // Set up test components.
 function setUp() {
   // Mock LoadTimeData strings.
   window.loadTimeData.getString = id => id;
+  window.loadTimeData.getBoolean = key => false;
 
   const mockTask = /** @type {!chrome.fileManagerPrivate.FileTask} */ ({
     taskId: 'handler-extension-id|app|any',