Fix a few spelling errors in comments.

ppapi/tests/test_instance_deprecated.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/tests/test_instance_deprecated.h"
 
 #include <assert.h>
 
 #include "ppapi/c/ppb_var.h"
 #include "ppapi/cpp/module.h"
@@ skipping 56 matching lines @@
     : TestCase(instance),
       instance_so_(NULL) {}
 
 bool TestInstance::Init() {
   return true;
 }
 
 TestInstance::~TestInstance() {
   ResetTestObject();
   if (testing_interface_->IsOutOfProcess() == PP_FALSE) {
-    // This should cause the instance object's descructor to be called.
+    // This should cause the instance object's destructor to be called.
     testing_interface_->RunV8GC(instance_->pp_instance());
 
     // Test a post-condition which ensures the instance objects destructor is
     // called. This only works reliably in-process. Out-of-process, it only
     // can work when the renderer stays alive a short while after the plugin
     // instance is destroyed. If the renderer is being shut down, too much
     // happens asynchronously for the out-of-process case to work reliably. In
     // particular:
     //   - The Var ReleaseObject message is asynchronous.
     //   - The PPB_Var_Deprecated host-side proxy posts a task to actually
@@ skipping 175 matching lines @@
   // that it was set as expected.
   pp::Var result = instance()->ExecuteScript(
       "sessionStorage.getItem('instance_destroyed');");
   ASSERT_TRUE(result.is_string());
   ASSERT_EQ(std::string("true"), result.AsString());
   instance()->ExecuteScript("sessionStorage.removeItem('instance_destroyed');");
 
   PASS();
 }